Semiconductor device and method of forming encapsulated wafer level chip scale package (EWLCSP)

ABSTRACT

A semiconductor device has a semiconductor die and an encapsulant around the semiconductor die. A fan-in interconnect structure is formed over the semiconductor die while leaving the encapsulant devoid of the interconnect structure. The fan-in interconnect structure includes an insulating layer and a conductive layer formed over the semiconductor die. The conductive layer remains within a footprint of the semiconductor die. A portion of encapsulant is removed from over the semiconductor die. A backside protection layer is formed over a non-active surface of the semiconductor die after depositing the encapsulant. The backside protection layer is formed by screen printing or lamination. The backside protection layer includes an opaque, transparent, or translucent material. The backside protection layer is marked for alignment using a laser. A reconstituted panel including the semiconductor die is singulated through the encapsulant to leave encapsulant disposed over a sidewall of the semiconductor die.

CLAIM OF DOMESTIC PRIORITY

The present application is a division of U.S. patent application Ser.No. 14/627,347, now U.S. Pat. No. 9,704,769, filed Feb. 20, 2015, whichclaims the benefit of U.S. Provisional Application No. 61/945,739, filedFeb. 27, 2014, which applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to a semiconductor device and method of formingembedded or encapsulated wafer level chip scale packages (eWLCSP).

BACKGROUND OF THE INVENTION

Semiconductor devices are commonly found in modern electronic products.Semiconductor devices vary in the number and density of electricalcomponents. Discrete semiconductor devices generally contain one type ofelectrical component, e.g., light emitting diode (LED), small signaltransistor, resistor, capacitor, inductor, and power metal oxidesemiconductor field effect transistor (MOSFET). Integrated semiconductordevices typically contain hundreds to millions of electrical components.Examples of integrated semiconductor devices include microcontrollers,microprocessors, and various signal processing circuits.

Semiconductor devices perform a wide range of functions such as signalprocessing, high-speed calculations, transmitting and receivingelectromagnetic signals, controlling electronic devices, transformingsunlight to electricity, and creating visual images for televisiondisplays. Semiconductor devices are found in the fields ofentertainment, communications, power conversion, networks, computers,and consumer products. Semiconductor devices are also found in militaryapplications, aviation, automotive, industrial controllers, and officeequipment.

Semiconductor devices exploit the electrical properties of semiconductormaterials. The structure of semiconductor material allows the material'selectrical conductivity to be manipulated by the application of anelectric field or base current or through the process of doping. Dopingintroduces impurities into the semiconductor material to manipulate andcontrol the conductivity of the semiconductor device.

A semiconductor device contains active and passive electricalstructures. Active structures, including bipolar and field effecttransistors, control the flow of electrical current. By varying levelsof doping and application of an electric field or base current, thetransistor either promotes or restricts the flow of electrical current.Passive structures, including resistors, capacitors, and inductors,create a relationship between voltage and current necessary to perform avariety of electrical functions. The passive and active structures areelectrically connected to form circuits, which enable the semiconductordevice to perform high-speed operations and other useful functions.

Semiconductor devices are generally manufactured using two complexmanufacturing processes, i.e., front-end manufacturing and back-endmanufacturing, each involving potentially hundreds of steps. Front-endmanufacturing involves the formation of a plurality of die on thesurface of a semiconductor wafer. Each semiconductor die is typicallyidentical and contains circuits formed by electrically connecting activeand passive components. Back-end manufacturing involves singulatingindividual semiconductor die from the finished wafer and packaging thedie to provide structural support, electrical interconnect, andenvironmental isolation. The term “semiconductor die” as used hereinrefers to both the singular and plural form of the words, andaccordingly, can refer to both a single semiconductor device andmultiple semiconductor devices.

One goal of semiconductor manufacturing is to produce smallersemiconductor devices. Smaller devices typically consume less power,have higher performance, and can be produced more efficiently. Inaddition, smaller semiconductor devices have a smaller footprint, whichis desirable for smaller end products. A smaller semiconductor die sizecan be achieved by improvements in the front-end process resulting insemiconductor die with smaller, higher density active and passivecomponents. Back-end processes may result in semiconductor devicepackages with a smaller footprint by improvements in electricalinterconnection and packaging materials.

One approach to achieving smaller semiconductor devices is the waferlevel chip scale package (WLCSP). A conventional semiconductor wafertypically contains a plurality of semiconductor die separated by a sawstreet. An interconnect structure can be formed over the surface of thesemiconductor wafer. The semiconductor wafer is processed by applyingpolymers, such as polyimide (PI) or polybenzoxazole (PBO), andredistribution layers to the wafer prior to singulation into WLCSP. PIhas a typical curing temperature of 380 degrees Celsius (° C.) and PBOhas a typical curing temperature of 300° C. PI and PBO are unsuitablefor using in manufacturing processes with temperature tolerances lowerthan, for example, 300° C. After singulation of the semiconductor waferinto WLCSP, the bare silicon of the semiconductor die is exposed on theremaining sidewalls and back side. The fragile nature of exposed siliconin WLCSP devices is a concern in surface mount technology (SMT) assemblyprocesses. The semiconductor die is subject to damage or degradation ifa portion of the semiconductor die is exposed to external elements,particularly when surface mounting the die. For example, thesemiconductor die can be damaged or degraded during handling or byexposure to light. Damage to the exposed silicon remains a problem forWLCSP and for advanced node products with fragile dielectric layers.Semiconductor die are also subject to damage during singulation ofsemiconductor wafers through the silicon or semiconductor material andinto individual WLCSP. Singulation through semiconductor material cancause cracking or chipping of the semiconductor die. Testing ofsingulated WLCSP involves high cost and long testing time due to thehandling of individual packages.

An important aspect of semiconductor manufacturing is high yield andcorresponding low cost. The yield of a WLCSP process is limited by thenature of processing an incoming semiconductor wafer, which typicallycontains a number of semiconductor die having defects. In a WLCSPprocess, the defective semiconductor die are processed together with thefunctional semiconductor die on the semiconductor wafer. Afterprocessing and singulation into WLCSP, the WLCSP containing defectivesemiconductor die are discarded. Thus, the number of functionalsemiconductor die on the incoming semiconductor wafer limits theachievable yield from a WLCSP process. For example, an incoming waferwith 15% defective semiconductor die results in a maximum yield of 85%of functional WLCSP. Thus, the wafer-level processing of WLCSPinherently includes waste in processing defective semiconductor die,which increases the unit cost of manufacturing WLCSPs.

Semiconductor wafers are fabricated having various diameters andsemiconductor die sizes and quantities. Semiconductor packagingequipment is typically developed according to each particular incomingsemiconductor wafer size or semiconductor die quantity or size. Forexample, a 200 millimeter (mm) wafer is processed using 200 mmequipment, and a 300 mm wafer is processed using 300 mm equipment.Equipment for packaging semiconductor devices is limited in processingcapability to the specific semiconductor wafer size or semiconductor diequantity and size for which the equipment is designed. As incomingsemiconductor wafer sizes and semiconductor die sizes change, additionalinvestment in manufacturing equipment is necessary. For example, smallersemiconductor die typically also have smaller, more advanced nodes.WLCSP processes are limited in the size of semiconductor die and nodetechnology that can be processed into a WLCSP. In particular, advancednode semiconductor die may fall outside the design limits of WLCSP. Whenthe design limits of WLCSP are exceeded, the design is conventionallychanged over to a different package type, such as leadframe-based orsubstrate-based package types. A change to the fundamental design of thepackage may have a substantial impact on device footprint, form factor,and performance characteristics. Significant re-design of a package,such as changing to a different package type, also increases overallcost of manufacturing the semiconductor device. Investment in equipmentfor a specific size of semiconductor die, size of semiconductor wafer,or quantity of semiconductor die creates capital investment risk forsemiconductor device manufacturers. As incoming semiconductor wafersizes change, wafer-specific equipment becomes obsolete. Similarly,carriers and equipment designed for specific sizes and quantities ofsemiconductor die can become obsolete, because the carriers are limitedin capability to handle different sizes and quantities of semiconductordie. Constant development and implementation of different equipment toaccommodate changing wafer and die sizes increases the cost ofmanufacturing semiconductor devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a printed circuit board (PCB) with different types ofpackages mounted to a surface of the PCB;

FIGS. 2a-2d illustrate a semiconductor wafer with a plurality ofsemiconductor die separated by a saw street;

FIGS. 3a-3i illustrate a method of forming an eWLCSP with a thinbackside encapsulant layer and thin sidewall encapsulation;

FIG. 4 illustrates an eWLCSP with a backside encapsulant layer and thinsidewall encapsulation;

FIGS. 5a-5e illustrate a method of forming an eWLCSP with thin sidewallencapsulation and exposed back surface of a semiconductor die;

FIGS. 6a-6d illustrate a method of forming an eWLCSP with thin sidewallencapsulation and a backside protection layer;

FIGS. 7a-7b illustrate a method of forming high density reconstitutedpanels on a standardized carrier;

FIGS. 8a-8g illustrate a method of using a standardized carrier to forma plurality of eWLCSP on a high density reconstituted panel;

FIGS. 9a-9f illustrate another method of using a standardized carrier toform a plurality of eWLCSP on a high density reconstituted panel;

FIGS. 10a-10c illustrate an alternative semiconductor wafer with aplurality of semiconductor die separated by a saw street;

FIGS. 11a-11i illustrate a method of forming a fan-in eWLCSP with abackside protection layer;

FIG. 12a-12b illustrate a plan view of an eWLCSP;

FIG. 13 illustrates an eWLCSP with an exposed back surface of asemiconductor die;

FIG. 14 illustrates an eWLCSP with backside encapsulant; and

FIG. 15 illustrates another fan-in eWLCSP with a backside protectionlayer.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving objectives of theinvention, those skilled in the art will appreciate that the disclosureis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and claims equivalents as supported by the followingdisclosure and drawings.

Semiconductor devices are generally manufactured using two complexmanufacturing processes: front-end manufacturing and back-endmanufacturing. Front-end manufacturing involves the formation of aplurality of die on the surface of a semiconductor wafer. Each die onthe wafer contains active and passive electrical components, which areelectrically connected to form functional electrical circuits. Activeelectrical components, such as transistors and diodes, have the abilityto control the flow of electrical current. Passive electricalcomponents, such as capacitors, inductors, and resistors, create arelationship between voltage and current necessary to perform electricalcircuit functions.

Passive and active components are formed over the surface of thesemiconductor wafer by a series of process steps including doping,deposition, photolithography, etching, and planarization. Dopingintroduces impurities into the semiconductor material by techniques suchas ion implantation or thermal diffusion. The doping process modifiesthe electrical conductivity of semiconductor material in active devicesby dynamically changing the semiconductor material conductivity inresponse to an electric field or base current. Transistors containregions of varying types and degrees of doping arranged as necessary toenable the transistor to promote or restrict the flow of electricalcurrent upon the application of the electric field or base current.

Active and passive components are formed by layers of materials withdifferent electrical properties. The layers can be formed by a varietyof deposition techniques determined in part by the type of materialbeing deposited. For example, thin film deposition can involve chemicalvapor deposition (CVD), physical vapor deposition (PVD), electrolyticplating, and electroless plating processes. Each layer is generallypatterned to form portions of active components, passive components, orelectrical connections between components.

Back-end manufacturing refers to cutting or singulating the finishedwafer into the individual semiconductor die and packaging thesemiconductor die for structural support, electrical interconnect, andenvironmental isolation. To singulate the semiconductor die, the waferis scored and broken along non-functional regions of the wafer calledsaw streets or scribes. The wafer is singulated using a laser cuttingtool or saw blade. After singulation, the individual semiconductor dieare mounted to a package substrate that includes pins or contact padsfor interconnection with other system components. Contact pads formedover the semiconductor die are then connected to contact pads within thepackage. The electrical connections can be made with conductive layers,bumps, stud bumps, conductive paste, or wirebonds. An encapsulant orother molding material is deposited over the package to provide physicalsupport and electrical isolation. The finished package is then insertedinto an electrical system and the functionality of the semiconductordevice is made available to the other system components.

FIG. 1 illustrates electronic device 50 having a chip carrier substrateor PCB 52 with a plurality of semiconductor packages mounted on asurface of PCB 52. Electronic device 50 can have one type ofsemiconductor package, or multiple types of semiconductor packages,depending on the application. The different types of semiconductorpackages are shown in FIG. 1 for purposes of illustration.

Electronic device 50 can be a stand-alone system that uses thesemiconductor packages to perform one or more electrical functions.Alternatively, electronic device 50 can be a subcomponent of a largersystem. For example, electronic device 50 can be part of a tablet,cellular phone, digital camera, or other electronic device.Alternatively, electronic device 50 can be a graphics card, networkinterface card, or other signal processing card that can be insertedinto a computer. The semiconductor package can include microprocessors,memories, application specific integrated circuits (ASIC),microelectromechanical systems (MEMS), logic circuits, analog circuits,radio frequency (RF) circuits, discrete devices, or other semiconductordie or electrical components. Miniaturization and weight reduction areessential for the products to be accepted by the market. The distancebetween semiconductor devices may be decreased to achieve higherdensity.

In FIG. 1, PCB 52 provides a general substrate for structural supportand electrical interconnect of the semiconductor packages mounted on thePCB. Conductive signal traces 54 are formed over a surface or withinlayers of PCB 52 using evaporation, electrolytic plating, electrolessplating, screen printing, or other suitable metal deposition process.Signal traces 54 provide for electrical communication between each ofthe semiconductor packages, mounted components, and other externalsystem components. Traces 54 also provide power and ground connectionsto each of the semiconductor packages.

In some embodiments, a semiconductor device has two packaging levels.First level packaging is a technique for mechanically and electricallyattaching the semiconductor die to an intermediate substrate. Secondlevel packaging involves mechanically and electrically attaching theintermediate substrate to the PCB. In other embodiments, a semiconductordevice may only have the first level packaging where the die ismechanically and electrically mounted directly to the PCB.

For the purpose of illustration, several types of first level packaging,including bond wire package 56 and flipchip 58, are shown on PCB 52.Additionally, several types of second level packaging, including ballgrid array (BGA) 60, bump chip carrier (BCC) 62, land grid array (LGA)66, multi-chip module (MCM) 68, quad flat non-leaded package (QFN) 70,quad flat package 72, embedded wafer level ball grid array (eWLB) 74,and WLCSP 76 are shown mounted on PCB 52. In one embodiment, eWLB 74 isa fan-out wafer level package (Fo-WLP) and WLCSP 76 is a fan-in waferlevel package (Fi-WLP). Depending upon the system requirements, anycombination of semiconductor packages, configured with any combinationof first and second level packaging styles, as well as other electroniccomponents, can be connected to PCB 52. In some embodiments, electronicdevice 50 includes a single attached semiconductor package, while otherembodiments call for multiple interconnected packages. By combining oneor more semiconductor packages over a single substrate, manufacturerscan incorporate pre-made components into electronic devices and systems.Because the semiconductor packages include sophisticated functionality,electronic devices can be manufactured using less expensive componentsand a streamlined manufacturing process. The resulting devices are lesslikely to fail and less expensive to manufacture resulting in a lowercost for consumers.

FIG. 2a shows a semiconductor wafer 110 with a base substrate material112, such as silicon, germanium, aluminum phosphide, aluminum arsenide,gallium arsenide, gallium nitride, indium phosphide, silicon carbide, orother bulk semiconductor material for structural support. A plurality ofsemiconductor die or components 114 is formed on wafer 110 separated bya non-active, inter-die wafer area or saw street 116 as described above.Saw street 116 provides cutting areas to singulate semiconductor wafer110 into individual semiconductor die 114. In one embodiment,semiconductor wafer 110 has a width or diameter of 100-450 mm.Semiconductor wafer 110 has any diameter prior to singulatingsemiconductor wafer into individual semiconductor die 114. Semiconductordie 114 may have any size, and in one embodiment, semiconductor die 114includes dimensions of 2.5 mm by 2.5 mm. In another embodiment,semiconductor die 114 includes dimensions of 6 mm by 6 mm.

FIG. 2a further shows a semiconductor wafer 120 with a base substratematerial 122, such as silicon, germanium, aluminum phosphide, aluminumarsenide, gallium arsenide, gallium nitride, indium phosphide, siliconcarbide, or other bulk semiconductor material for structural support. Aplurality of semiconductor die or components 124 is formed on wafer 120separated by a non-active, inter-die wafer area or saw street 126 asdescribed above. Saw street 126 provides cutting areas to singulatesemiconductor wafer 120 into individual semiconductor die 124.Semiconductor wafer 120 may have the same diameter or a differentdiameter from semiconductor wafer 110. In one embodiment, semiconductorwafer 120 has a width or diameter of 100-450 mm. Semiconductor wafer 120has any diameter prior to singulating semiconductor wafer intoindividual semiconductor die 124. Semiconductor die 124 have the samesize or a different size from semiconductor die 114. Semiconductor die124 may have any size, and in one embodiment, semiconductor die 124include dimensions of 4.5 mm by 4.5 mm.

FIG. 2b shows a cross-sectional view of a portion of semiconductor wafer120. Each semiconductor die 124 has a back or non-active surface 128 andan active surface 130 containing analog or digital circuits implementedas active devices, passive devices, conductive layers, and dielectriclayers formed within the die and electrically interconnected accordingto the electrical design and function of the die. For example, thecircuit may include one or more transistors, diodes, and other circuitelements formed within active surface 130 to implement analog circuitsor digital circuits, such as digital signal processor (DSP), ASIC, MEMS,memory, or other signal processing circuit. In one embodiment, activesurface 130 contains a MEMS, such as an accelerometer, strain gauge,microphone, or other sensor responsive to various external stimuli.Semiconductor die 124 may also contain integrated passive devices(IPDs), such as inductors, capacitors, and resistors, for RF signalprocessing. Back surface 128 of semiconductor wafer 120 may undergo anoptional backgrinding operation with a mechanical grinding or etchingprocess to remove a portion of base material 122 and reduce thethickness of semiconductor wafer 120 and semiconductor die 124.

An electrically conductive layer 132 is formed over active surface 130using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 132 can be oneor more layers of aluminum (Al), copper (Cu), tin (Sn), nickel (Ni),gold (Au), silver (Ag), titanium (Ti), or other suitable electricallyconductive material. Conductive layer 132 operates as contact padselectrically connected to the circuits on active surface 130. Conductivelayer 132 can be formed as contact pads disposed side-by-side a firstdistance from the edge of semiconductor die 124, as shown in FIG. 2b .Alternatively, conductive layer 132 can be formed as contact pads thatare offset in multiple rows such that a first row of contact pads isdisposed a first distance from the edge of the die, and a second row ofcontact pads alternating with the first row is disposed a seconddistance from the edge of the die.

A first insulating or passivation layer 134 is formed over semiconductordie 124 and conductive layer 132 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 134contains one or more layers of silicon dioxide (SiO2), silicon nitride(Si3N4), silicon oxynitride (SiON), tantalum pentoxide (Ta2O5), aluminumoxide (Al2O3), hafnium oxide (HfO2), benzocyclobutene (BCB), PI, PBO, orother polymer or dielectric material having similar structural andinsulating properties. A portion of insulating layer 134 is removed bylaser direct ablation (LDA) using laser 136 or an etching processthrough a patterned photoresist layer to expose conductive layer 132 andprovide for subsequent electrical interconnect.

Semiconductor wafer 120 undergoes electrical testing and inspection aspart of a quality control process. Manual visual inspection andautomated optical systems are used to perform inspections onsemiconductor wafer 120. Software can be used in the automated opticalanalysis of semiconductor wafer 120. Visual inspection methods mayemploy equipment such as a scanning electron microscope, high-intensityor ultra-violet light, or metallurgical microscope. Semiconductor wafer120 is inspected for structural characteristics including warpage,thickness variation, surface particulates, irregularities, cracks,delamination, and discoloration.

The active and passive components within semiconductor die 124 undergotesting at the wafer level for electrical performance and circuitfunction. Each semiconductor die 124 is tested for functionality andelectrical parameters, as shown in FIG. 2c , using a test probe head 140including a plurality of probes or test leads 142, or other testingdevice. Probes 142 are used to make electrical contact with nodes orconductive layer 132 on each semiconductor die 124 and provideelectrical stimuli to contact pads 132. Semiconductor die 124 respondsto the electrical stimuli, which is measured by computer test system 144and compared to an expected response to test functionality of thesemiconductor die. The electrical tests may include circuitfunctionality, lead integrity, resistivity, continuity, reliability,junction depth, electro-static discharge (ESD), RF performance, drivecurrent, threshold current, leakage current, and operational parametersspecific to the component type. The inspection and electrical testing ofsemiconductor wafer 120 enables semiconductor die 124 that pass to bedesignated as known good die (KGD) for use in a semiconductor package.

In FIG. 2d , semiconductor wafer 120 is singulated through saw street126 using a saw blade or laser cutting tool 146 into individualsemiconductor die 124. After singulation, side surfaces or sidewalls 148of semiconductor die 124 are exposed. The individual semiconductor die124 can be inspected and electrically tested for identification of KGDpost singulation.

FIGS. 3a-3i illustrate, in relation to FIGS. 1 and 2 a-2 d, a process offorming a fan-in eWLCSP. FIG. 3a shows a cross-sectional view of aportion of a carrier or temporary substrate 150 containing sacrificialbase material such as silicon, polymer, beryllium oxide, glass, metal,or other suitable low-cost, rigid material for structural support. Aninterface layer or double-sided tape 152 is formed over carrier 150 as atemporary adhesive bonding film, etch-stop layer, or thermal releaselayer. In one embodiment, carrier 150 includes a metal, and interfacelayer 152 includes an adhesive foil laminated onto carrier 150.

Carrier 150 can be a round or rectangular panel (300 mm or greater) withcapacity for multiple semiconductor die 124. Carrier 150 may have alarger surface area than the surface area of semiconductor wafer 120. Alarger carrier reduces the manufacturing cost of the semiconductorpackage as more semiconductor die can be processed on the larger carrierthereby reducing the cost per unit. Semiconductor packaging andprocessing equipment are designed and configured for the size of thewafer or carrier being processed.

To further reduce manufacturing costs, the size of carrier 150 isselected independent of the size of semiconductor die 124 or size ofsemiconductor wafer 120. That is, carrier 150 has a fixed orstandardized size, which can accommodate various size semiconductor die124 singulated from one or more semiconductor wafers 120. In oneembodiment, carrier 150 is circular with a diameter of approximately 300mm. In another embodiment, carrier 150 is rectangular with a width of560 mm and length of 600 mm. The larger surface area of carrier 150accommodates more semiconductor die 124 and lowers manufacturing cost asmore semiconductor die 124 are processed per reconstituted panel 156.Semiconductor die 124 may have dimensions of 4.5 mm by 4.5 mm, which areplaced on the standardized carrier 150. In another embodiment,semiconductor die 124 may have dimensions of 2.5 mm by 2.5 mm, which areplaced on the same standardized carrier 150. Accordingly, standardizedcarrier 150 can handle any size semiconductor die 124, which allowssubsequent semiconductor processing equipment to be standardized to acommon carrier, i.e., independent of die size or incoming wafer size.Semiconductor packaging equipment can be designed and configured for astandard carrier using a common set of processing tools, equipment, andbill of materials to process any semiconductor die size from anyincoming wafer size. The common or standardized carrier 150 lowersmanufacturing costs and capital risk by reducing or eliminating the needfor specialized semiconductor processing lines based on die size orincoming wafer size. By selecting a predetermined carrier size to usefor any size semiconductor die from all semiconductor wafer sizes, aflexible manufacturing line can be implemented.

In FIG. 3a , semiconductor die 124 from FIG. 2d are mounted to interfacelayer 152 and over carrier 150 using, for example, a pick and placeoperation with active surface 130 oriented toward the carrier.Semiconductor die 124 are placed onto carrier 150 separated by a gap 154with a distance D₁ between adjacent semiconductor die 124. Distance D₁between semiconductor die 124 is selected based on the design andspecifications of the semiconductor package to be processed. Gap 154 ordistance D₁ between semiconductor die 124 allows for a thin protectivelayer of encapsulant to remain over sidewalls 148 after singulation. Inone embodiment, distance D₁ is sufficient to provide sidewall coverageby an encapsulant plus a saw street area for singulation. For example,to produce 30 micrometers (μm) of sidewall coverage for eachsemiconductor die 124 and to provide an 80 μm saw street forsingulation, the distance D₁ of gap 154 is selected to be approximately140 μm. In another embodiment, distance D₁ between semiconductor die 124is 100 μm or less. In yet another embodiment, distance D₁ betweensemiconductor die 124 is greater than approximately 100 μm. Distance D₁of gap 154 between semiconductor die 124 on carrier 150 is optimized formanufacturing the semiconductor packages at the lowest unit cost.

FIG. 3a shows semiconductor die 124 disposed over interface layer 152 ofcarrier 150 as reconstituted panel or reconfigured wafer 156.Reconstituted wafer or panel 156 can be processed into many types ofsemiconductor packages, including eWLB, fan-in WLCSP, eWLCSP, fan-outWLCSP, flipchip packages, three dimensional (3D) packages,package-on-package (PoP), or other semiconductor packages. Semiconductordie 124 are selected from KGD, which are singulated from one or moresemiconductor wafers 120 and mounted to carrier 150. The use of KGD inreconstituted wafer 156 improves the yield of the resultingsemiconductor packages, thereby reducing the package cost.

Carrier 150 further reduces manufacturing costs because standardizedprocessing equipment can be used to process any configuration ofsemiconductor die on carrier 150. Reconstituted panel 156 is configuredaccording to the specifications of the resulting semiconductor package.The number of semiconductor die 124 disposed over carrier 150 depends onthe size of semiconductor die 124 and distance D₁ between semiconductordie 124 within reconstituted wafer 156. In one embodiment, semiconductordie 124 are placed on carrier 150 in a high-density arrangement, i.e., adistance D₁ of 300 μm or less, for processing fan-in devices. The numberof semiconductor die 124 mounted to carrier 150 can be greater than,less than, or equal to the number of semiconductor die 124 singulatedfrom a semiconductor wafer 120. Carrier 150 accommodates differentquantities and sizes of semiconductor die as well as different distancesbetween semiconductor die. Accordingly, carrier 150 is independent ofthe size of semiconductor wafer 120, the size of semiconductor die 124,the quantity of semiconductor die 124 singulated from semiconductorwafer 120, and the final package type. Carrier 150 and reconstitutedpanel 156 provide the flexibility to manufacture many different types ofsemiconductor packages with different size semiconductor die 124 fromdifferent size semiconductor wafers 120 using standardized equipment.

In FIG. 3b , an encapsulant or molding compound 158 is deposited oversemiconductor die 124 and carrier 150 as an insulating material using apaste printing, compressive molding, transfer molding, liquidencapsulant molding, vacuum lamination, spin coating, or other suitableapplicator. Encapsulant 158 includes polymer composite material, such asepoxy resin with filler, epoxy acrylate with filler, or polymer withproper filler. Encapsulant 158 is non-conductive and environmentallyprotects the semiconductor device from external elements andcontaminants. In one embodiment, encapsulant 158 includes an opaquematerial and is dark or black in color to provide protection ofsemiconductor die 124 from light and to prevent soft errors byattenuating photon injection.

Encapsulant 158 is deposited into gap 154 and covers sidewalls 148 ofsemiconductor die 124, while active surface 130 is oriented towardcarrier 150 and remains protected. Encapsulant 158 is deposited overback surface 128 of semiconductor die 124 with a deposited thickness T₁,which is measured from back surface 128 of semiconductor die 124 to backsurface 160 of encapsulant 158. In one embodiment, the depositedthickness T₁ of encapsulant 158 over back surface 128 of semiconductordie 124 is approximately 100 μm or greater. In another embodiment,deposited thickness T₁ of encapsulant 158 over back surface 128 ofsemiconductor die 124 is approximately 105 μm. Encapsulant 158 contactsinterface layer 152 such that surface 162 of encapsulant 158, oppositeback surface 160, is formed coplanar with active surface 130 ofsemiconductor die 124.

In FIG. 3c , temporary carrier 150 and interface layer 152 are removedby chemical etching, mechanical peel-off, chemical mechanicalplanarization (CMP), mechanical grinding, thermal bake, laser scanning,or wet stripping. Temporary carrier 150 and interface layer 152 areremoved from over surface 162 of encapsulant 158 and active surface 130of semiconductor die 124 to expose conductive layer 132, insulatinglayer 134, and surface 162 of encapsulant 158.

An insulating or passivation layer 170 is formed over insulating layer134 and conductive layer 132 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 170 canbe one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxybased photosensitive polymer dielectric, low temperature (≤200° C.)curable polymer, or other material having similar insulating andstructural properties. In one embodiment, insulating layer 170 includesa low temperature curing photosensitive dielectric polymer with orwithout insulating fillers cured at less than 200° C. Insulating layer170 is formed over active surface 130 of semiconductor die 124 andsurface 162 of encapsulant 158. A portion of insulating layer 170 isremoved by an etching process with a patterned photoresist layer or byLDA to expose conductive layer 132 with respect to insulating layer 170.In another embodiment, a portion of insulating layer 170 is also removedfrom over encapsulant 158 such that surface 162 of encapsulant 158 isexposed and devoid of insulating layer 170. In one embodiment,insulating layer 170 includes a thickness ranging from approximately7-11 μm.

In FIG. 3d , an electrically conductive layer 172 is formed overinsulating layer 170 and contact pads 132 using a patterning and metaldeposition process such as PVD, CVD, sputtering, electrolytic plating,and electroless plating. Conductive layer 172 can be one or more layersof Al, Cu, Sn, Ni, Au, Ag, or other suitable electrically conductivematerial. Conductive layer 172 operates as a redistribution layer (RDL)to redistribute the electrical signals of semiconductor die 124.Conductive layer 172 is formed within a footprint of semiconductor die124 and does not extend beyond the footprint of semiconductor die 124 orover surface 162 of encapsulant 158. In other words, a peripheral regionof semiconductor die 124 adjacent to semiconductor die 124 is devoid ofconductive layer 172. One portion of conductive layer 172 iselectrically connected to contact pads 132 of semiconductor die 124.Other portions of conductive layer 172 can be electrically common orelectrically isolated depending on the design and function of thesemiconductor device. In one embodiment, conductive layer 172 includes athickness ranging from approximately 7-10 μm.

An insulating or passivation layer 174 is formed over insulating layer170 and conductive layer 172 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 174 canbe one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxybased photosensitive polymer dielectric, low temperature (≤200° C.)curable polymer, or other material having similar insulating andstructural properties. In one embodiment, insulating layer 174 includesa low temperature curing photosensitive dielectric polymer with orwithout insulating fillers cured at less than 200° C. Insulating layer174 is formed over active surface 130 of semiconductor die 124 andsurface 162 of encapsulant 158. A portion of insulating layer 174 isremoved by an etching process with a patterned photoresist layer or byLDA to expose conductive layer 172 with respect to insulating layer 174.In another embodiment, a portion of insulating layer 174 is also removedfrom over encapsulant 158 such that surface 162 of encapsulant 158 isexposed and devoid of insulating layer 174. In one embodiment,insulating layer 174 includes a thickness ranging from approximately7-11 μm.

Insulating layers 170 and 174 together with conductive layer 172constitute a build-up interconnect structure 176. Interconnect structure176 is formed over active surface 130 of semiconductor die 124 andsurface 162 of encapsulant 158 and directly on conductive layer 132 andinsulating layer 134. Interconnect structure 176 may include fewer oradditional conductive and insulating layers. In one embodiment, theelectrical interconnection of interconnect structure 176 remainsentirely within a footprint of semiconductor die 124. A peripheralregion outside a footprint of semiconductor die 124 is devoid ofelectrical interconnect thereby resulting in a fan-in interconnectstructure 176.

In FIG. 3e , an electrically conductive bump material is deposited overconductive layer 172 of interconnect structure 176 and is electricallyconnected to conductive layer 132 using an evaporation, electrolyticplating, electroless plating, ball drop, or screen printing process. Thebump material can be Al, Sn, Ni, Au, Ag, lead (Pb), bismuth (Bi), Cu,solder, and combinations thereof, with an optional flux solution. Forexample, the bump material can be eutectic Sn/Pb, high-lead solder, orlead-free solder. The bump material is bonded to conductive layer 172using a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form spherical balls or bumps 178. In some applications, bumps178 are reflowed a second time to improve electrical contact toconductive layer 172. The bumps can also be compression bonded toconductive layer 172. Bumps 178 represent one type of interconnectstructure that can be formed over conductive layer 172. The interconnectstructure can also use bond wires, stud bump, micro bump, or otherelectrical interconnect.

In FIG. 3f , reconstituted panel 156 undergoes an optional backgrindingstep. A backgrinding or support tape 180 is applied over interconnectstructure 176 and in contact with insulating layer 174 and bumps 178. Aportion of encapsulant 158 is removed in a grinding operation withgrinder 182 to planarize the surface of encapsulant 158. A chemical etchor CMP process can also be used to planarize encapsulant 158 and toremove mechanical damage resulting from the grinding operation. In oneembodiment, the backgrinding operation removes a portion of encapsulant158 from surface 160 while leaving another portion of encapsulant 158disposed over back surface 128 of semiconductor die 124. The removal ofa portion of encapsulant 158 leaves new back surface 184 of encapsulant158. The backgrinding operation reduces a thickness of encapsulant 158from deposited thickness T₁ to a reduced thickness T₂, which is measuredfrom back surface 128 of semiconductor die 124 to new back surface 184of encapsulant 158. Encapsulant 158 remaining over back surface 128 ofsemiconductor die 124 includes a reduced thickness T₂ of approximately105 μm or less. Alternatively, reduced thickness T₂ is greater thanapproximately 100 μm. In another embodiment, the backgrinding operationcompletely removes encapsulant 158 from over semiconductor die 124 toexpose back surface 128 of semiconductor die 124. Removing a portion ofencapsulant 158 reduces warpage of reconstituted panel 156. Lasermarking is applied over encapsulant 158 or directly to back surface 128of semiconductor die 124 for alignment and singulation. Laser marking ofencapsulant 158 improves the visibility of the marking. Laser markingcan be performed before or after bump formation, or before or afterremoval of carrier 150.

In FIG. 3g , reconstituted panel 156 is singulated with saw blade orlaser cutting device 190 into individual semiconductor devices or eWLCSP192. Reconstituted panel 156 is singulated through encapsulant 158 andthrough insulating layers 170 and 174 of interconnect structure 176.Singulating through encapsulant 158 removes a portion of encapsulant 158from saw street 194 while a thin layer of encapsulant 158 remainsdisposed over sidewalls 148 of semiconductor die 124. eWLCSP 192undergoes electrical testing before or after singulation. Because eWLCSP192 are singulated through encapsulant 158, eWLCSP 192 are subject toless damage during singulation. With less risk of damage duringsingulation, testing can be performed prior to singulation and expensiveinspection steps can be eliminated from the final testing of each eWLCSP192. By testing prior to singulating reconstituted panel 156, eWLCSP 192can be tested at the reconstituted wafer level. Wafer level testingreduces cost of testing by reducing the handling and testing timecompared to pick and place handling and testing of singulated packages.

FIG. 3h shows a cross-sectional view of eWLCSP 192 after singulation.eWLCSP 192 includes encapsulant 158 formed over back surface 128 andsidewalls 148 of semiconductor die 124. Semiconductor die 124 iselectrically connected through conductive layers 132 and 172 to bumps178 for external interconnect through interconnect structure 176.Conductive layer 174 of interconnect structure 176 and bumps 178 remainwithin a footprint of semiconductor die 124 to form a fan-in package.Insulating layer 170 is formed over insulating layer 134 ofsemiconductor die 124 and over encapsulant 158 to cover the interfacebetween semiconductor die 124 and encapsulant 158 and to protect theinterface during processing and improve the reliability of eWLCSP 192.In another embodiment, interconnect structure 176 is formed completelywithin a footprint of semiconductor die 124.

Encapsulant 158 remains over sidewalls 148 and back surface 128 formechanical protection of semiconductor die 124 and protection from lightor other emissions. Encapsulant 158 is disposed over back surface 128 ofsemiconductor die 124 after an optional grinding operation. Encapsulant158 operates as a backside protection layer for semiconductor die 124. Athin layer of encapsulant 158 remains disposed over sidewalls 148 ofsemiconductor die 124 after singulation. Encapsulant 158 over sidewalls148 has a thickness T₃ of less than approximately 100 μm. Therefore,encapsulant 158 is disposed over five sides of semiconductor die 124,i.e., over four side surfaces 148 and over back surface 128.

FIG. 3i shows an enlarged cross-sectional view of a portion of eWLCSP192 from FIG. 3h . Encapsulant 158 over back surface 128 ofsemiconductor die 124 includes a reduced thickness T₂ of approximately105 μm or less. Semiconductor die 124 includes a height H₁, measuredfrom active surface 130 to back surface 128. In one embodiment, a heightH₁ of semiconductor die 124 is approximately 350 μm or less. Encapsulant158 over sidewalls 148 of semiconductor die 124 includes a thickness T₃,measured from a sidewall 148 of semiconductor die 124 to an edge 196 ofeWLCSP 192. In one embodiment, encapsulant 158 over sidewalls 148 ofsemiconductor die 124 includes a thickness T₃ of approximately 70 μm orless. In another embodiment, a thickness T₃ of encapsulant 158 oversidewalls 148 ranges from approximately 30-50 μm. In one embodiment,thickness T₂ of encapsulant 158 over back surface 128 of semiconductordie 124 is greater than thickness T₃ of encapsulant 158 over sidewalls148 of semiconductor die 124.

Encapsulant 158 disposed over sidewalls 148 and back surface 128increases the strength of semiconductor die 124 by providing mechanicalprotection during package assembly and singulation operations and duringsurface mounting and end use of eWLCSP 192. Encapsulant 158 oversidewalls 148 mitigates cracking and chipping of semiconductor die 124within eWLCSP 192. Encapsulant 158 further protects semiconductor die124 from degradation due to exposure to light or other emissions. Thesmall footprint of eWLCSP 192 is similar in size to a WLCSP withoutsidewall protection, because thickness T₃ of encapsulant 158 oversidewalls 148 results in a negligible increase in package size foreWLCSP 192. In one embodiment, the package footprint size of eWLCSP 192is within 100 μm in the x- and y-directions of a WLCSP without sidewallencapsulant. Thus, eWLCSP 192 maintains a small package size whileimproving the reliability of the device. Additionally, eWLCSP 192 formedon reconstituted panel 156 has shorter testing time, a greater yield,and lower manufacturing cost than standard wafer-level devices.

FIG. 4 shows an alternative eWLCSP 198. Semiconductor die 124 includesconductive layer 132 and insulating layer 134 formed over active surface130 with openings in insulating layer 134 formed over conductive layer132. Encapsulant 158 is deposited over and around semiconductor die 124.Interconnect structure 176 includes conductive layer 172 and insulatinglayers 170 and 174 and is formed over active surface 130 ofsemiconductor die 124. Bumps 178 are formed over conductive layer 172 ofinterconnect structure 176. Semiconductor die 124 is electricallyconnected through conductive layers 132 and 172, to bumps 178 forexternal interconnect through interconnect structure 176. Conductivelayer 174 of interconnect structure 176 and bumps 178 remain within afootprint of semiconductor die 124 to form a fan-in package.

Encapsulant 158 is deposited over back surface 128 of semiconductor die124 with a deposited thickness T₁. Encapsulant 158 operates as abackside protection layer for semiconductor die 124. In one embodiment,a deposited thickness T₁ of encapsulant 158 over back surface 128 isapproximately 170-230 μm or less. Where the optional backgrinding stepis not used in the process of making eWLCSP 198, a deposited thicknessT₁ of encapsulant 158 remains over back surface 128 of semiconductor die124. Without a backgrinding step, the cost of manufacturing eWLCSP 198is reduced. A thin layer of encapsulant 158 remains disposed oversidewalls 148 of semiconductor die 124 after singulation. Encapsulant158 over sidewalls 148 has a thickness T₃ of less than approximately 100μm. In one embodiment, encapsulant 158 over sidewalls 148 ofsemiconductor die 124 includes a thickness T₃ of approximately 70 μm orless. In another embodiment, a thickness T₃ of encapsulant 158 oversidewalls 148 ranges from approximately 30-50 μm. Therefore, encapsulant158 is disposed over five sides of semiconductor die 124, i.e., overfour side surfaces 148 and over back surface 128.

Encapsulant 158 disposed over sidewalls 148 and back surface 128increases the strength of semiconductor die 124 by providing mechanicalprotection during the package assembly and singulation operations andduring surface mounting and end use of eWLCSP 198. Encapsulant 158 oversidewalls 148 and back surface 128 mitigates cracking and chipping ofsemiconductor die 124 within eWLCSP 198. Encapsulant 158 furtherprotects semiconductor die 124 from degradation due to exposure to lightor other emissions. The small footprint of eWLCSP 198 is similar in sizeto a WLCSP without sidewall protection, because thickness T₃ ofencapsulant 158 over sidewalls 148 results in a negligible increase inpackage size for eWLCSP 198. In one embodiment, the package footprintsize of eWLCSP 198 is within 100 μm in the x- and y-directions of aWLCSP without sidewall encapsulant. Thus, eWLCSP 198 maintains a smallpackage size while improving the reliability of the device.Additionally, eWLCSP 198 formed on reconstituted panel 156 has shortertesting time, a greater yield, and lower manufacturing cost thanstandard wafer-level devices.

FIGS. 5a-5e illustrate, in relation to FIGS. 1 and 2 a-2 d, analternative process of making an eWLCSP with an exposed back surface ofa semiconductor die. Continuing from FIG. 3e , FIG. 5a showsreconstituted panel 156 with semiconductor die 124 embedded inencapsulant 158 and with an interconnect structure 176 formed overactive surface 130 of semiconductor die 124 and surface 162 ofencapsulant 158.

In FIG. 5a , a backgrinding tape or support tape 200 is applied overinterconnect structure 176 and in contact with insulating layer 174 andbumps 178. A portion of encapsulant 158 is removed in a grindingoperation with grinder 202 to planarize the surface of encapsulant 158and expose back surface 128 of semiconductor die 124. A chemical etch orCMP process can also be used to planarize encapsulant 158 and to removemechanical damage resulting from the grinding operation. The removal ofa portion of encapsulant 158 from surface 160 leaves new back surface204 of encapsulant 158. Encapsulant 158 is completely removed from overback surface 128 of semiconductor die 124 to expose back surface 128 ofsemiconductor die 124. After backgrinding, a new back surface 204 ofencapsulant 158 is substantially coplanar with back surface 128 ofsemiconductor die 124. Reconstituted panel 156 has a reduced thicknessafter the backgrinding operation. A thickness of semiconductor die 124can also be reduced by the backgrinding operation. In one embodiment, aportion of back surface 128 of semiconductor die 124 is removed to thinsemiconductor die 124 during the backgrinding operation. Removing aportion of encapsulant 158 reduces warpage of reconstituted panel 156.Laser marking can be applied directly to back surface 128 ofsemiconductor die 124 for alignment and singulation.

FIG. 5b shows reconstituted panel 156 after a backgrinding operation.Back surface 128 of semiconductor die 124 is exposed with respect toencapsulant 158. Surface 204 of encapsulant 158 is substantiallycoplanar with back surface 128 of semiconductor die 124.

In FIG. 5c , reconstituted panel 156 is singulated with saw blade orlaser cutting device 210 into individual semiconductor devices or eWLCSP212. Reconstituted panel 156 is singulated through encapsulant 158 andinsulating layers 170 and 174 of interconnect structure 176. Singulatingthrough encapsulant 158 removes a portion of encapsulant 158 from sawstreet 214 while a thin layer of encapsulant 158 remains disposed oversidewalls 148 of semiconductor die 124. eWLCSP 212 undergoes electricaltesting before or after singulation. Because eWLCSP 212 are singulatedthrough encapsulant 158, eWLCSP 212 are subject to less damage duringsingulation. With less risk of damage during singulation, testing can beperformed prior to singulation and expensive inspection steps can beeliminated from the final testing of each eWLCSP 212. By testing priorto singulating reconstituted panel 156, eWLCSP 212 can be tested at thereconstituted wafer level. Wafer level testing reduces cost of testingby reducing the handling and testing time compared to pick and placehandling and testing of singulated packages.

FIG. 5d shows a cross-sectional view of eWLCSP 212 after singulation.eWLCSP 212 includes encapsulant 158 formed over sidewalls 148 ofsemiconductor die 124. Semiconductor die 124 is electrically connectedthrough conductive layers 132 and 172 to bumps 178 for externalinterconnect through interconnect structure 176. Conductive layer 174 ofinterconnect structure 176 and bumps 178 remain within a footprint ofsemiconductor die 124 to form a fan-in package. Insulating layer 170 isformed over insulating layer 134 of semiconductor die 124 and overencapsulant 158 to cover the interface between semiconductor die 124 andencapsulant 158 and to protect the interface during processing andimprove the reliability of eWLCSP 212. In another embodiment,interconnect structure 176 is formed completely within a footprint ofsemiconductor die 124.

A thin layer of encapsulant 158 remains disposed over sidewalls 148 ofsemiconductor die 124 after singulation. Encapsulant 158 over sidewalls148 has a thickness T₃ of less than approximately 100 μm. Encapsulant158 is disposed over four sides of semiconductor die 124, i.e., over thefour sidewalls 148. Encapsulant 158 remaining over sidewalls 148provides mechanical protection for semiconductor die 124. eWLCSP 212with an exposed back surface 128 of semiconductor die 124 has a reducedheight or profile compared to devices with a backside protection layer.

FIG. 5e shows an enlarged cross-section view of a portion of eWLCSP 212from FIG. 5d . Encapsulant 158 over sidewalls 148 of semiconductor die124 includes a thickness T₃, measured from sidewall 148 of semiconductordie 124 to an edge 216 of eWLCSP 212. In one embodiment, encapsulant 158over sidewalls 148 of semiconductor die 124 includes a thickness T₃ ofapproximately 70 μm or less. In another embodiment, a thickness T₃ ofencapsulant 158 over sidewalls 148 ranges from approximately 30-50 μm.Encapsulant 158 disposed over sidewalls 148 increases the strength ofsemiconductor die 124 by providing mechanical protection during thepackage assembly and singulation operations and during surface mountingand end use of eWLCSP 212. Encapsulant 158 over sidewalls 148 mitigatescracking and chipping of semiconductor die 124 within eWLCSP 212. Thesmall footprint of eWLCSP 212 is similar in size to a WLCSP withoutsidewall protection, because thickness T₃ of encapsulant 158 oversidewalls 148 results in a negligible increase in package size foreWLCSP 212. In one embodiment, the package footprint size of eWLCSP 212is within 100 μm in the x- and y-directions of a WLCSP without sidewallencapsulant. Additionally, eWLCSP 212 formed on reconstituted panel 156has shorter testing time, a greater yield, and lower manufacturing costthan standard wafer-level devices.

FIGS. 6a-6d illustrate, in relation to FIGS. 1 and 2 a-2 d, analternative process of making an eWLCSP with a backside protectionlayer. Continuing from FIG. 5b , FIG. 6a shows reconstituted panel 156after a backgrinding process. Semiconductor die 124 are embedded inencapsulant 158 and encapsulant 158 is removed from over back surface128 of semiconductor die 124 to expose back surface 128. Reconstitutedpanel 156 is disposed over backgrinding tape 200 for support during thebackgrinding operation. A thickness of semiconductor die 124 can also bereduced by the backgrinding operation.

In FIG. 6b , a backside protection layer 220 is formed over back surface128 of semiconductor die 124 and surface 204 of encapsulant 158 forprotection of semiconductor die 124. Backside protection layer 220 maycontain one or more layers of photosensitive low curing temperaturedielectric resist, photosensitive composite resist, laminate compoundfilm, resin matrix composite sheet with filler or glass fiber cloth,resin matrix composite sheet with both filler and glass fiber cloth,insulation paste with filler, solder mask resist film, liquid moldingcompound, granular molding compound, polyimide, BCB, SiO2, Si3N4, SiON,Ta2O5, Al2O3, prepreg, or other dielectric material having similarinsulating and structural properties. Backside protection layer 220 isdeposited using spin coating, screen printing, spray coating, vacuum orpressure lamination with or without heat, transfer molding, or othersuitable process. In one embodiment, backside protection layer 220 is alow temperature curing photosensitive dielectric polymer with or withoutinsulating fillers cured at less than 200° C. In another embodiment,backside protection layer 220 is cured by ultraviolet light (UV).Alternatively, backside protection layer 220 is a metal layer, such asCu foil, applied to a backside of reconstituted panel 156. Backsideprotection layer 220 contacts back surface 128 of semiconductor die 124to transfer heat from semiconductor die 124 and improve the thermalperformance of the device.

Backside protection layer 220 is formed after singulation ofsemiconductor wafer 120 and reconstitution of semiconductor die 124, andprior to singulation of reconstituted panel 156. In one embodiment,backside protection layer 220 includes an opaque material and is dark orblack in color to provide protection of semiconductor die 124 fromphotons from light and other emissions to reduce soft errors. Backsideprotection layer 220 can be used for laser marking reconstituted panel156 and improves visibility of marking on the back surface of thereconstituted panel 156. In another embodiment, backside protectionlayer 220 includes a transparent or translucent material.

For semiconductor die 124 with optical properties, such as an LED, atransparent backside protection 220 layer allows photon emission fromback surface 128 of semiconductor die 124 through backside protectionlayer 220. In one embodiment, the base material 122 of semiconductor die124 includes sapphire, and semiconductor die 124 includes activeelements on active surface 130. In a flip-chip application, light may beemitted through backside protection layer 220 and through base material122 of semiconductor die 124. Back surface 128 of semiconductor die 124is coated with a translucent or transparent backside protection layer220. The translucent or transparent backside protection layer 220provides mechanical protection of semiconductor die 124, while allowinglight transmission through backside protection layer 220.

In FIG. 6c , reconstituted panel 156 is singulated with saw blade orlaser cutting device 222 into individual semiconductor devices or eWLCSP224. Reconstituted panel 156 is singulated through encapsulant 158 andinsulating layers 170 and 174 of interconnect structure 176. Singulatingthrough encapsulant 158 removes a portion of encapsulant 158 from sawstreet 226 while a thin layer of encapsulant 158 remains disposed oversidewalls 148 of semiconductor die 124. eWLCSP 224 undergoes electricaltesting before or after singulation. Because eWLCSP 224 are singulatedthrough encapsulant 158, eWLCSP 224 are subject to less damage duringsingulation. With less risk of damage during singulation, testing can beperformed prior to singulation and expensive inspection steps can beeliminated from the final testing of each eWLCSP 224. By testing priorto singulating reconstituted panel 156, eWLCSP 224 can be tested at thereconstituted wafer level. Wafer level testing reduces cost of testingby reducing the handling and testing time compared to pick and placehandling and testing of singulated packages.

FIG. 6d shows a cross-sectional view of eWLCSP 224 after singulation.eWLCSP 224 includes encapsulant 158 formed over sidewalls 148 ofsemiconductor die 124. An interconnect structure 176 is formed overactive surface 130 of semiconductor die 124 and surface 162 ofencapsulant 158. Bumps 178 are formed over conductive layer 172 ofinterconnect structure 176. Semiconductor die 124 is electricallyconnected through conductive layers 132 and 172 to bumps 178 forexternal interconnect through interconnect structure 176. Conductivelayer 174 of interconnect structure 176 and bumps 178 remain within afootprint of semiconductor die 124 to form a fan-in package. Insulatinglayer 170 is formed over insulating layer 134 of semiconductor die 124and over encapsulant 158 to cover the interface between semiconductordie 124 and encapsulant 158 and to protect the interface duringprocessing and improve the reliability of eWLCSP 224. In anotherembodiment, interconnect structure 176 is formed completely within afootprint of semiconductor die 124.

A thin layer of encapsulant 158 remains disposed over sidewalls 148after singulation. Encapsulant 158 is disposed over four sides ofsemiconductor die 124, i.e., over the four sidewalls 148, and backsideprotection layer 220 is disposed over back surface 128 resulting infive-sided protection of semiconductor die 124. Encapsulant 158 oversidewalls 148 of semiconductor die 124 includes a thickness T₃, measuredfrom a sidewall 148 of semiconductor die 124 to an edge 228 of eWLCSP224. In one embodiment, a thickness T₃ of encapsulant 158 over sidewalls148 is less than approximately 100 μm. In another embodiment,encapsulant 158 over sidewalls 148 of semiconductor die 124 includes athickness T₃ of approximately 70 μm or less. In yet another embodiment,a thickness T₃ of encapsulant 158 over sidewalls 148 ranges fromapproximately 30-50 μm. Backside protection layer 220 is disposed overback surface 128 and provides mechanical protection for semiconductordie 124. Backside protection layer 220 may protect semiconductor die 124from light. Backside protection layer 220 includes a thickness T₄ overback surface 128 of semiconductor die 124 and over encapsulant 158. Inone embodiment, backside protection layer 220 has a thickness T₄ rangingfrom approximately 5-150 μm. In another embodiment, backside protectionlayer 220 has a thickness T₄ of greater than approximately 30 μm. In yetanother embodiment, backside protection layer 220 has a thickness T₄ ofapproximately 120 μm or less. Backside protection layer 220 improves thestrength and reduces chipping of semiconductor die 124. eWLCSP 224 withbackside protection layer 220 may be formed with a reduced height orprofile compared to devices with a backside encapsulant.

Encapsulant 158 and backside protection layer 220 increase the strengthof semiconductor die 124 by providing mechanical protection during thepackage assembly and singulation operations and during surface mountingand end use of eWLCSP 224. Encapsulant 158 over sidewalls 148 mitigatescracking and chipping of semiconductor die 124 within eWLCSP 224. Anopaque encapsulant 158 and backside protection layer 220 further protectsemiconductor die 124 from degradation due to exposure to light or otheremissions. Alternatively, a transparent or translucent encapsulant 158and backside protection layer 220 provide light transmission forsemiconductor die 124 having optical properties. The small footprint ofeWLCSP 224 is similar in size to a WLCSP without sidewall protection,because thickness T₃ of encapsulant 158 over sidewalls 148 results in anegligible increase in package size for eWLCSP 224. In one embodiment,the package footprint size of eWLCSP 224 is within 100 μm in the x- andy-directions of a WLCSP without sidewall encapsulant. Additionally,eWLCSP 224 formed on reconstituted panel 156 has shorter testing time, agreater yield, and lower manufacturing cost than standard wafer-leveldevices.

FIGS. 7a-7b illustrate, in relation to FIGS. 1 and 2 a-2 d, a process offorming high density reconstituted panels on a standardized carrier. InFIG. 7a , semiconductor die 124 from FIG. 2d are mounted to interfacelayer 152 and over carrier 150 using, for example, a pick and placeoperation with active surface 130 oriented toward the carrier.Semiconductor die 124 are placed onto carrier 150 separated by a gap 230with distance D₂ between semiconductor die 124. Distance D₂ betweensemiconductor die 124 is selected based on the design and specificationsof the semiconductor package to be processed. Gap 230 or distance D₂between semiconductor die 124 allows for a thin protective layer ofencapsulant to remain over sidewalls 148 after singulation. In oneembodiment, distance D₂ is sufficient to provide sidewall coverage by anencapsulant plus a saw street area for singulation. For example, toproduce 30 μm of sidewall coverage for each semiconductor die 124 and toprovide an 80 μm saw street for singulation, the distance D₂ of gap 230is selected to be approximately 140 μm. In another embodiment, distanceD₂ between semiconductor die 124 is 100 μm or less. In yet anotherembodiment, distance D₂ between semiconductor die 124 is greater thanapproximately 100 μm. Distance D₂ of gap 230 between semiconductor die124 on carrier 150 is optimized for manufacturing the semiconductorpackages at the lowest unit cost. Semiconductor die 124 mounted tocarrier 150 form a reconstituted panel or reconfigured wafer 232.

FIG. 7b shows an alternative arrangement of semiconductor die 124 formFIG. 2d mounted to interface layer 152 and over carrier 150 using, forexample, a pick and place operation with active surface 130 orientedtoward the carrier. Semiconductor die 124 are placed onto carrier 150separated by a gap 234 with distance D₃ between semiconductor die 124.In one embodiment, distance D₃ is sufficient to provide sidewallcoverage by an encapsulant plus a saw street area for singulation. D₃ isincreased to provide a greater thickness of sidewall encapsulant, toaccommodate advanced node semiconductor die, or to accommodate a greaterquantity or a higher density of input/output (I/O) connections. In oneembodiment, distance D₃ between semiconductor die 124 is greater thanapproximately 100 μm. In another embodiment, distance D₃ betweensemiconductor die 124 is 100 μm or less. Distance D₃ of gap 234 betweensemiconductor die 124 on carrier 150 is optimized for manufacturing thesemiconductor packages at the lowest unit cost. Semiconductor die 124mounted to carrier 150 form a reconstituted panel or reconfigured wafer236.

Reconstituted panels 232 and 236 can be processed into many types ofsemiconductor packages, including eWLB, fan-in WLCSP, eWLCSP, fan-outWLCSP, flipchip packages, 3D packages, PoP, or other semiconductorpackages. Reconstituted panels 232 and 236 are configured according tothe specifications of the resulting semiconductor package. In oneembodiment, semiconductor die 124 are placed on carrier 150 in ahigh-density arrangement, i.e., 300 μm apart or less, for processingfan-in devices. The larger surface area of carrier 150 accommodates moresemiconductor die 124 and lowers manufacturing cost as moresemiconductor die 124 are processed per reconstituted panel. The numberof semiconductor die 124 mounted to carrier 150 can be greater than thenumber of semiconductor die 124 singulated from semiconductor wafer 120.Carrier 150 and reconstituted panels 232 and 236 provide the flexibilityto manufacture many different types of semiconductor packages usingdifferent size semiconductor die 124 from different sized semiconductorwafers 120.

FIGS. 8a-8g illustrate, in relation to FIGS. 1 and 2 a-2 d, a process offorming an eWLCSP with fine pitch interconnects. Continuing from FIG. 7a, FIG. 8a shows reconstituted panel 232 with semiconductor die 124disposed over interface layer 152 and carrier 150 with a distance D₂between adjacent semiconductor die 124.

In FIG. 8a , an encapsulant or molding compound 238 is deposited oversemiconductor die 124 and carrier 150 as an insulating material using apaste printing, compressive molding, transfer molding, liquidencapsulant molding, vacuum lamination, spin coating, or other suitableapplicator. Encapsulant 238 includes polymer composite material, such asepoxy resin with filler, epoxy acrylate with filler, or polymer withproper filler. Encapsulant 238 is non-conductive and environmentallyprotects the semiconductor device from external elements andcontaminants. In one embodiment, encapsulant 238 includes an opaquematerial and is dark or black in color to provide protection ofsemiconductor die 124 from light and to prevent soft errors byattenuating photon injection. Encapsulant 238 is deposited into gap 230and covers sidewalls 148 of semiconductor die 124, while active surface130 is oriented toward carrier 150 and remains protected. Encapsulant238 is formed with a back surface 240 over reconstituted panel 232 andcovers back surface 128 of semiconductor die 124. Encapsulant 238contacts interface layer 152 such that surface 242 of encapsulant 238,opposite back surface 240, is formed coplanar with active surface 130 ofsemiconductor die 124.

In FIG. 8b , temporary carrier 150 and interface layer 152 are removedby chemical etching, mechanical peel-off, CMP, mechanical grinding,thermal bake, laser scanning, or wet stripping. Temporary carrier 150and interface layer 152 are removed from over surface 242 of encapsulant238 and active surface 130 of semiconductor die 124 to expose conductivelayer 132, insulating layer 134, and surface 242 of encapsulant 238.

A build-up interconnect structure 250 is formed over semiconductor die124 and encapsulant 238. An insulating or passivation layer 252 isformed over insulating layer 134 and conductive layer 132 using PVD,CVD, printing, spin coating, spray coating, sintering or thermaloxidation. Insulating layer 252 can be one or more layers of SiO2,Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxy based photosensitive polymerdielectric, low temperature (≤200° C.) curable polymer, or othermaterial having similar insulating and structural properties. In oneembodiment, insulating layer 252 includes a low temperature curingphotosensitive dielectric polymer with or without insulating fillerscured at less than 200° C. Insulating layer 252 is formed over activesurface 130 of semiconductor die 124 and surface 242 of encapsulant 238.A portion of insulating layer 252 is removed by an etching process witha patterned photoresist layer or by LDA to expose conductive layer 132with respect to insulating layer 252. In another embodiment, a portionof insulating layer 252 is also removed from over encapsulant 238 suchthat surface 242 of encapsulant 238 is exposed and devoid of insulatinglayer 252. In one embodiment, insulating layer 252 includes a thicknessranging from approximately 7-11 μm.

An electrically conductive layer 254 is formed over insulating layer 252and contact pads 132 using a patterning and metal deposition processsuch as PVD, CVD, sputtering, electrolytic plating, and electrolessplating. Conductive layer 254 can be one or more layers of Al, Cu, Sn,Ni, Au, Ag, or other suitable electrically conductive material.Conductive layer 254 operates as an RDL to redistribute the electricalsignals of semiconductor die 124. Conductive layer 254 is formed withina footprint of semiconductor die 124 and does not extend beyond thefootprint of semiconductor die 124 or over surface 242 of encapsulant238. In other words, a peripheral region of semiconductor die 124adjacent to semiconductor die 124 is devoid of conductive layer 254. Oneportion of conductive layer 254 is electrically connected to contactpads 132 of semiconductor die 124. Other portions of conductive layer254 can be electrically common or electrically isolated depending on thedesign and function of the semiconductor device. In one embodiment,conductive layer 254 includes a thickness ranging from approximately7-10 μm.

An insulating or passivation layer 256 is formed over insulating layer252 and conductive layer 254 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 256 canbe one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxybased photosensitive polymer dielectric, low temperature (≤200° C.)curable polymer, or other material having similar insulating andstructural properties. In one embodiment, insulating layer 256 includesa low temperature curing photosensitive dielectric polymer with orwithout insulating fillers cured at less than 200° C. Insulating layer256 is formed over active surface 130 of semiconductor die 124 andsurface 242 of encapsulant 238. A portion of insulating layer 256 isremoved by an etching process with a patterned photoresist layer or byLDA to expose conductive layer 254 with respect to insulating layer 256.In another embodiment, a portion of insulating layer 256 is also removedfrom over encapsulant 238 such that surface 242 of encapsulant 238 isexposed and devoid of insulating layer 256. In one embodiment,insulating layer 256 includes a thickness ranging from approximately7-11 μm.

An electrically conductive bump material is deposited over conductivelayer 254 of interconnect structure 250 and is electrically connected toconductive layer 132 using an evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, and combinationsthereof, with an optional flux solution. For example, the bump materialcan be eutectic Sn/Pb, high-lead solder, or lead-free solder. The bumpmaterial is bonded to conductive layer 254 using a suitable attachmentor bonding process. In one embodiment, the bump material is reflowed byheating the material above its melting point to form spherical balls orbumps 258 a-258 b. In some applications, bumps 258 a-258 b are refloweda second time to improve electrical contact to conductive layer 254. Thebumps can also be compression bonded to conductive layer 254. Bumps 258a-258 b represent one type of interconnect structure that can be formedover conductive layer 254. The interconnect structure can also use bondwires, stud bump, micro bump, or other electrical interconnect.

In FIG. 8c , reconstituted panel 232 undergoes an optional backgrindingstep. A backgrinding tape or support tape 260 is applied overinterconnect structure 250 and in contact with insulating layer 256 andbumps 258 a-258 b. A portion of encapsulant 238 is removed in a grindingoperation with grinder 262 to planarize the surface of encapsulant 238and expose back surface 128 of semiconductor die 124. A chemical etch orCMP process can also be used to planarize encapsulant 238 and to removemechanical damage resulting from the grinding operation. The removal ofa portion of encapsulant 238 leaves new back surface 264 of encapsulant238. Encapsulant 238 is completely removed from over back surface 128 ofsemiconductor die 124 to expose back surface 128 of semiconductor die124. After backgrinding, a new back surface 264 of encapsulant 238 iscoplanar with back surface 128 of semiconductor die 124. Reconstitutedpanel 232 has a reduced thickness after the backgrinding operation. Athickness of semiconductor die 124 can also be reduced by thebackgrinding operation. In one embodiment, a portion of back surface 128of semiconductor die 124 is removed to thin semiconductor die 124 duringthe backgrinding operation. Removing a portion of encapsulant 238reduces warpage of reconstituted panel 232. Laser marking can be applieddirectly to back surface 128 of semiconductor die 124 for alignment andsingulation.

In FIG. 8d , a backside protection layer 266 is formed over back surface128 of semiconductor die 124 and surface 264 of encapsulant 238 forprotection of semiconductor die 124. Backside protection layer 266 maycontain one or more layers of photosensitive low curing temperaturedielectric resist, photosensitive composite resist, laminate compoundfilm, resin matrix composite sheet with filler or glass fiber cloth,resin matrix composite sheet with both filler and glass fiber cloth,insulation paste with filler, solder mask resist film, liquid moldingcompound, granular molding compound, polyimide, BCB, SiO2, Si3N4, SiON,Ta2O5, Al2O3, prepreg, or other dielectric material having similarinsulating and structural properties. Backside protection layer 266 isdeposited using spin coating, screen printing, spray coating, vacuum orpressure lamination with or without heat, transfer molding, or othersuitable process. In one embodiment, backside protection layer 266 is alow temperature curing photosensitive dielectric polymer with or withoutinsulating fillers cured at less than 200° C. In another embodiment,backside protection layer 266 is cured by UV. Alternatively, backsideprotection layer 266 is a metal layer, such as Cu foil, applied to abackside of reconstituted panel 232. Backside protection layer 266contacts back surface 128 of semiconductor die 124 to transfer heat fromsemiconductor die 124 and improve the thermal performance of the device.

Backside protection layer 266 is formed after singulation ofsemiconductor wafer 120 and reconstitution of semiconductor die 124, andprior to singulation of reconstituted panel 232. In one embodiment,backside protection layer 266 includes an opaque material and is dark orblack in color to provide protection of semiconductor die 124 fromphotons from light and other emissions to reduce soft errors. Backsideprotection layer 266 can be used for laser marking reconstituted panel232 and improves visibility of marking on the back surface of thereconstituted panel 232. In another embodiment, backside protectionlayer 266 includes a transparent or translucent material.

For semiconductor die 124 with optical properties, such as an LED, atransparent backside protection 266 layer allows photon emission fromback surface 128 of semiconductor die 124 through backside protectionlayer 266. In one embodiment, the base material 122 of semiconductor die124 includes sapphire, and semiconductor die 124 includes activeelements on active surface 130. In a flip-chip application, light may beemitted through backside protection layer 266 and through base material122 of semiconductor die 124. Back surface 128 of semiconductor die 124is coated with a translucent or transparent backside protection layer266. The translucent or transparent backside protection layer 266provides mechanical protection of semiconductor die 124, while allowinglight transmission through backside protection layer 266.

In FIG. 8e , reconstituted panel 232 is singulated with saw blade orlaser cutting device 270 into individual semiconductor devices or eWLCSP272 a-272 b. Reconstituted panel 232 is singulated through encapsulant238, insulating layers 252 and 256 of interconnect structure 250, andbackside protection layer 266. Singulating through encapsulant 238removes a portion of encapsulant 238 from saw street 274 while a thinlayer of encapsulant 238 remains disposed over sidewalls 148 ofsemiconductor die 124. eWLCSP 272 a-272 b undergo electrical testingbefore or after singulation.

The process of forming eWLCSP 272 a-272 b on reconstituted panel 232allows a variety of semiconductor die 124 to be processed using carrier150, including advanced node semiconductor die with nodes down to 22nanometer (nm). For example, eWLCSP 272 a-272 b may be formed with agreater I/O densities and smaller I/O pitches that are outside thedesign limits for conventional WLCSP. The process of forming eWLCSP 272a-272 b accommodates transitions to different I/O densities and pitcheswithin the same or similar packaging process using a standardizedcarrier, such as carrier 150. Additionally, because eWLCSP 272 a-272 bare singulated through encapsulant 238, eWLCSP 272 a-272 b are subjectto less damage during singulation. With less risk of damage duringsingulation, expensive inspection steps can be eliminated from the finaltesting of each eWLCSP 272 a-272 b. By testing prior to singulatingreconstituted panel 232, eWLCSP 272 a-272 b can be tested at thereconstituted wafer level. Wafer level testing reduces cost of testingby reducing the handling and testing time compared to pick and placehandling and testing of singulated packages.

FIG. 8f shows a cross-sectional view of eWLCSP 272 a after singulation.eWLCSP 272 a includes encapsulant 238 formed over sidewalls 148 ofsemiconductor die 124. An interconnect structure 250 is formed overactive surface 130 of semiconductor die 124 and surface 242 ofencapsulant 238. Bumps 258 a are formed over conductive layer 254 ofinterconnect structure 250. Semiconductor die 124 is electricallyconnected through conductive layers 132 and 254 to bumps 258 a forexternal interconnect through interconnect structure 250. Conductivelayer 254 of interconnect structure 250 and bumps 258 a remain within afootprint of semiconductor die 124 to form a fan-in package. Insulatinglayer 252 is formed over insulating layer 134 of semiconductor die 124and over encapsulant 238 to cover the interface between semiconductordie 124 and encapsulant 238 and to protect the interface duringprocessing and improve the reliability of eWLCSP 272 a. In anotherembodiment, interconnect structure 250 is formed completely within afootprint of semiconductor die 124. eWLCSP 272 a accommodates highdensity I/O and fine pitch I/O. In one embodiment, bumps 258 a have apitch P₁ of approximately 0.4 mm or less and a density of approximately6 I/O per square millimeter (mm²) or greater. In another embodiment,bumps 258 a have a pitch P₁ of approximately 0.5 mm or less and adensity of approximately 4 I/O/mm² or greater.

A thin layer of encapsulant 238 remains disposed over sidewalls 148after singulation. Encapsulant 238 is disposed over four sides ofsemiconductor die 124, i.e., over the four sidewalls 148, and backsideprotection layer 266 is disposed over back surface 128 resulting infive-sided protection of semiconductor die 124. Backside protectionlayer 266 is disposed over back surface 128 and provides mechanicalprotection for semiconductor die 124. Backside protection layer 266 mayprotect semiconductor die 124 from light. Backside protection layer 266includes a thickness T₅ over back surface 128 of semiconductor die 124and over encapsulant 238. In one embodiment, backside protection layer266 has a thickness T₅ ranging from approximately 5-150 μm. In anotherembodiment, backside protection layer 266 has a thickness T₅ of greaterthan approximately 30 μm. In yet another embodiment, backside protectionlayer 266 has a thickness T₅ of approximately 120 μm or less.Encapsulant 238 over sidewalls 148 of semiconductor die 124 includes athickness T₆, measured from a sidewall 148 of semiconductor die 124 toan edge 276 of eWLCSP 272 a. In one embodiment, a thickness T₆ ofencapsulant 238 over sidewalls 148 is less than approximately 100 μm. Inanother embodiment, encapsulant 238 over sidewalls 148 of semiconductordie 124 includes a thickness T₆ of approximately 70 μm or less. In yetanother embodiment, a thickness T₆ of encapsulant 238 over sidewalls 148ranges from approximately 30-50 μm. Backside protection layer 266 andsidewall encapsulant 238 improve the strength and reduce chipping ofsemiconductor die 124. eWLCSP 272 a with backside protection layer 266may be formed with a reduced height or profile compared to devices witha backside encapsulant.

Encapsulant 238 and backside protection layer 266 increase the strengthof semiconductor die 124 by providing mechanical protection during thepackage assembly and singulation operations and during surface mountingand end use of eWLCSP 272 a. Encapsulant 238 over sidewalls 148mitigates cracking and chipping of semiconductor die 124 within eWLCSP272 a. An opaque encapsulant 238 and backside protection layer 266further protect semiconductor die 124 from degradation due to exposureto light or other emissions. Alternatively, a transparent or translucentencapsulant 238 and backside protection layer 266 provide lighttransmission for semiconductor die 124 having optical properties. Thesmall footprint of eWLCSP 272 a is similar in size to a WLCSP withoutsidewall protection, because thickness T₆ of encapsulant 238 oversidewalls 148 results in a negligible increase in package size foreWLCSP 272 a. In one embodiment, the package footprint size of eWLCSP272 a is within 100 μm in the x- and y-directions of a WLCSP withoutsidewall encapsulant. Additionally, eWLCSP 272 a formed on reconstitutedpanel 232 has shorter testing time, a greater yield, and lowermanufacturing cost than standard wafer-level devices.

FIG. 8g shows a cross-sectional view of eWLCSP 272 b after singulation.eWLCSP 272 b includes encapsulant 238 formed over sidewalls 148 ofsemiconductor die 124. An interconnect structure 250 is formed overactive surface 130 of semiconductor die 124 and surface 242 ofencapsulant 238. Bumps 258 b are formed over conductive layer 254 ofinterconnect structure 250. Semiconductor die 124 is electricallyconnected through conductive layers 132 and 254 to bumps 258 b forexternal interconnect through interconnect structure 250. Conductivelayer 254 of interconnect structure 250 and bumps 258 b remain within afootprint of semiconductor die 124 to form a fan-in package. Insulatinglayer 252 is formed over insulating layer 134 of semiconductor die 124and over encapsulant 238 to cover the interface between semiconductordie 124 and encapsulant 238 and to protect the interface duringprocessing and improve the reliability of eWLCSP 272 b. In anotherembodiment, interconnect structure 250 is formed completely within afootprint of semiconductor die 124. eWLCSP 272 b accommodates highdensity I/O and fine pitch I/O. In one embodiment, bumps 258 b have apitch P₂ of approximately 0.4 mm or less and a density of approximately6 I/O mm² or greater. In another embodiment, bumps 258 b have a pitch P₂of approximately 0.5 mm or less and a density of approximately 4 I/O/mm²or greater. eWLCSP 272 b may include a greater quantity of bumps 258 bor a smaller pitch P₂ of bumps 258 b than other packages, such as eWLCSP272 a from FIG. 8f , processed on the same carrier 150. Interconnectstructure 250 and bumps 258 b are formed closer to edge 148 ofsemiconductor die 124 to increase the density of bumps 258 b.Encapsulant 238 formed over sidewalls 148 results in less damage to thedevice during singulation and allows for finer pitch I/O.

A thin layer of encapsulant 238 remains disposed over sidewalls 148after singulation. Encapsulant 238 is disposed over four sides ofsemiconductor die 124, i.e., over the four sidewalls 148, and backsideprotection layer 266 is disposed over back surface 128 resulting infive-sided protection of semiconductor die 124. Backside protectionlayer 266 is disposed over back surface 128 and provides mechanicalprotection for semiconductor die 124. Backside protection layer 266 mayprotect semiconductor die 124 from light. Backside protection layer 266includes a thickness T₅ over back surface 128 of semiconductor die 124and over encapsulant 238. In one embodiment, backside protection layer266 has a thickness T₅ ranging from approximately 5-150 μm. In anotherembodiment, backside protection layer 266 has a thickness T₅ of greaterthan approximately 30 μm. In yet another embodiment, backside protectionlayer 266 has a thickness T₅ of approximately 120 μm or less.Encapsulant 238 over sidewalls 148 of semiconductor die 124 includes athickness T₆, measured from a sidewall 148 of semiconductor die 124 toan edge 276 of eWLCSP 272 b. In one embodiment, a thickness T₆ ofencapsulant 238 over sidewalls 148 is less than approximately 100 μm. Inanother embodiment, encapsulant 238 over sidewalls 148 of semiconductordie 124 includes a thickness T₆ of approximately 70 μm or less. In yetanother embodiment, a thickness T₆ of encapsulant 238 over sidewalls 148ranges from approximately 30-50 μm. Backside protection layer 266 andsidewall encapsulant 238 improve the strength and reduce chipping ofsemiconductor die 124. eWLCSP 272 b with backside protection layer 266may be formed with a reduced height or profile compared to devices witha backside encapsulant.

Encapsulant 238 and backside protection layer 266 increase the strengthof semiconductor die 124 by providing mechanical protection during thepackage assembly and singulation operations and during surface mountingand end use of eWLCSP 272 b. Encapsulant 238 over sidewalls 148mitigates cracking and chipping of semiconductor die 124 within eWLCSP272 b. An opaque encapsulant 238 and backside protection layer 266further protect semiconductor die 124 from degradation due to exposureto light or other emissions. Alternatively, a transparent or translucentencapsulant 238 and backside protection layer 266 provide lighttransmission for semiconductor die 124 having optical properties. Thesmall footprint of eWLCSP 272 b is similar in size to a WLCSP withoutsidewall protection, because thickness T₆ of encapsulant 238 oversidewalls 148 results in a negligible increase in package size foreWLCSP 272 b. In one embodiment, the package footprint size of eWLCSP272 b is within 100 μm in the x- and y-directions of a WLCSP withoutsidewall encapsulant. Additionally, eWLCSP 272 b formed on reconstitutedpanel 232 has shorter testing time, a greater yield, and lowermanufacturing cost than standard wafer-level devices.

FIGS. 9a-9f illustrate, in relation to FIGS. 1 and 2 a-2 d, a process offorming an eWLCSP with an additional row of interconnects. Continuingfrom FIG. 7b , FIG. 9a shows reconstituted panel 236 with semiconductordie 124 disposed over interface layer 152 and carrier 150 with adistance D₃ between adjacent semiconductor die 124.

In FIG. 9a , an encapsulant or molding compound 280 is deposited oversemiconductor die 124 and carrier 150 as an insulating material using apaste printing, compressive molding, transfer molding, liquidencapsulant molding, vacuum lamination, spin coating, or other suitableapplicator. Encapsulant 280 includes polymer composite material, such asepoxy resin with filler, epoxy acrylate with filler, or polymer withproper filler. Encapsulant 280 is non-conductive and environmentallyprotects the semiconductor device from external elements andcontaminants. In one embodiment, encapsulant 280 includes an opaquematerial and is dark or black in color to provide protection ofsemiconductor die 124 from light and to prevent soft errors byattenuating photon injection. Encapsulant 280 is deposited into gap 234and covers sidewalls 148 of semiconductor die 124, while active surface130 is oriented toward carrier 150 and remains protected. Encapsulant280 is formed with a back surface 282 over reconstituted panel 236 andcovers back surface 128 of semiconductor die 124. Encapsulant 280contacts interface layer 152 such that surface 284 of encapsulant 280,opposite back surface 282, is formed coplanar with active surface 130 ofsemiconductor die 124.

In FIG. 9b , temporary carrier 150 and interface layer 152 are removedby chemical etching, mechanical peel-off, CMP, mechanical grinding,thermal bake, laser scanning, or wet stripping. Temporary carrier 150and interface layer 152 are removed from over surface 284 of encapsulant280 and active surface 130 of semiconductor die 124 to expose conductivelayer 132, insulating layer 134, and surface 284 of encapsulant 280.

A build-up interconnect structure 290 is formed over semiconductor die124 and encapsulant 280. An insulating or passivation layer 292 isformed over insulating layer 134 and conductive layer 132 using PVD,CVD, printing, spin coating, spray coating, sintering or thermaloxidation. Insulating layer 292 can be one or more layers of SiO2,Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxy based photosensitive polymerdielectric, low temperature (≤200° C.) curable polymer, or othermaterial having similar insulating and structural properties. In oneembodiment, insulating layer 292 includes a low temperature curingphotosensitive dielectric polymer with or without insulating fillerscured at less than 200° C. Insulating layer 292 is formed over activesurface 130 of semiconductor die 124 and surface 284 of encapsulant 280.A portion of insulating layer 292 is removed by an etching process witha patterned photoresist layer or by LDA to expose conductive layer 132with respect to insulating layer 292. In another embodiment, a portionof insulating layer 292 is also removed from over encapsulant 280 suchthat surface 284 of encapsulant 280 is exposed and devoid of insulatinglayer 292. In one embodiment, insulating layer 292 includes a thicknessranging from approximately 7-11 μm.

An electrically conductive layer 294 is formed over insulating layer 292and contact pads 132 using a patterning and metal deposition processsuch as PVD, CVD, sputtering, electrolytic plating, and electrolessplating. Conductive layer 294 can be one or more layers of Al, Cu, Sn,Ni, Au, Ag, or other suitable electrically conductive material.Conductive layer 294 operates as an RDL to redistribute the electricalsignals of semiconductor die 124. Conductive layer 294 is formed withina footprint of semiconductor die 124 and does not extend beyond thefootprint of semiconductor die 124 or over surface 284 of encapsulant280. In other words, a peripheral region of semiconductor die 124adjacent to semiconductor die 124 is devoid of conductive layer 294. Oneportion of conductive layer 294 is electrically connected to contactpads 132 of semiconductor die 124. Other portions of conductive layer294 can be electrically common or electrically isolated depending on thedesign and function of the semiconductor device. In one embodiment,conductive layer 294 includes a thickness ranging from approximately7-10 μm.

An insulating or passivation layer 296 is formed over insulating layer292 and conductive layer 294 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 296 canbe one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxybased photosensitive polymer dielectric, low temperature (≤200° C.)curable polymer, or other material having similar insulating andstructural properties. In one embodiment, insulating layer 296 includesa low temperature curing photosensitive dielectric polymer with orwithout insulating fillers cured at less than 200° C. Insulating layer296 is formed over active surface 130 of semiconductor die 124 andsurface 284 of encapsulant 280. A portion of insulating layer 296 isremoved by an etching process with a patterned photoresist layer or byLDA to expose conductive layer 294 with respect to insulating layer 296.In another embodiment, a portion of insulating layer 296 is also removedfrom over encapsulant 280 such that surface 284 of encapsulant 280 isexposed and devoid of insulating layer 296. In one embodiment,insulating layer 296 includes a thickness ranging from approximately7-11 μm.

An electrically conductive bump material is deposited over conductivelayer 294 of interconnect structure 290 and is electrically connected toconductive layer 132 using an evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, and combinationsthereof, with an optional flux solution. For example, the bump materialcan be eutectic Sn/Pb, high-lead solder, or lead-free solder. The bumpmaterial is bonded to conductive layer 294 using a suitable attachmentor bonding process. In one embodiment, the bump material is reflowed byheating the material above its melting point to form spherical balls orbumps 298. In some applications, bumps 298 are reflowed a second time toimprove electrical contact to conductive layer 294. The bumps can alsobe compression bonded to conductive layer 294. Bumps 298 represent onetype of interconnect structure that can be formed over conductive layer294. The interconnect structure can also use bond wires, stud bump,micro bump, or other electrical interconnect.

In FIG. 9c , reconstituted panel 236 undergoes an optional backgrindingstep. A backgrinding tape or support tape 300 is applied overinterconnect structure 290 and in contact with insulating layer 296 andbumps 298. A portion of encapsulant 280 is removed in a grindingoperation with grinder 302 to planarize the surface of encapsulant 280and expose back surface 128 of semiconductor die 124. A chemical etch orCMP process can also be used to planarize encapsulant 280 and to removemechanical damage resulting from the grinding operation. Encapsulant 280is completely removed from over back surface 128 of semiconductor die124 to expose back surface 128 of semiconductor die 124. Afterbackgrinding, encapsulant 280 is coplanar with back surface 128 ofsemiconductor die 124. Reconstituted panel 236 has a reduced thicknessafter the backgrinding operation. A thickness of semiconductor die 124can also be reduced by the backgrinding operation. In one embodiment, aportion of back surface 128 of semiconductor die 124 is removed to thinsemiconductor die 124 during the backgrinding operation. Removing aportion of encapsulant 280 reduces warpage of reconstituted panel 236.Laser marking can be applied directly to back surface 128 ofsemiconductor die 124 for alignment and singulation.

In FIG. 9d , a backside protection layer 304 is formed over back surface128 of semiconductor die 124 and a back surface of encapsulant 280 forprotection of semiconductor die 124. Backside protection layer 304 maycontain one or more layers of photosensitive low curing temperaturedielectric resist, photosensitive composite resist, laminate compoundfilm, resin matrix composite sheet with filler or glass fiber cloth,resin matrix composite sheet with both filler and glass fiber cloth,insulation paste with filler, solder mask resist film, liquid moldingcompound, granular molding compound, polyimide, BCB, SiO2, Si3N4, SiON,Ta2O5, Al2O3, prepreg, or other dielectric material having similarinsulating and structural properties. Backside protection layer 304 isdeposited using spin coating, screen printing, spray coating, vacuum orpressure lamination with or without heat, transfer molding, or othersuitable process. In one embodiment, backside protection layer 304 is alow temperature curing photosensitive dielectric polymer with or withoutinsulating fillers cured at less than 200° C. In another embodiment,backside protection layer 304 is cured by UV. Alternatively, backsideprotection layer 304 is a metal layer, such as Cu foil, applied to abackside of reconstituted panel 236. Backside protection layer 304contacts back surface 128 of semiconductor die 124 to transfer heat fromsemiconductor die 124 and improve the thermal performance of the device.

Backside protection layer 304 is formed after singulation ofsemiconductor wafer 120 and reconstitution of semiconductor die 124, andprior to singulation of reconstituted panel 236. In one embodiment,backside protection layer 304 includes an opaque material and is dark orblack in color to provide protection of semiconductor die 124 fromphotons from light and other emissions to reduce soft errors. Backsideprotection layer 304 can be used for laser marking reconstituted panel236 and improves visibility of marking on the back surface of thereconstituted panel 236. In another embodiment, backside protectionlayer 304 includes a transparent or translucent material.

For semiconductor die 124 with optical properties, such as an LED, atransparent backside protection 304 layer allows photon emission fromback surface 128 of semiconductor die 124 through backside protectionlayer 304. In one embodiment, the base material 122 of semiconductor die124 includes sapphire, and semiconductor die 124 includes activeelements on active surface 130. In a flip-chip application, light may beemitted through backside protection layer 304 and through base material122 of semiconductor die 124. Back surface 128 of semiconductor die 124is coated with a translucent or transparent backside protection layer304. The translucent or transparent backside protection layer 304provides mechanical protection of semiconductor die 124, while allowinglight transmission through backside protection layer 304.

In FIG. 9e , reconstituted panel 236 is singulated with saw blade orlaser cutting device 306 into individual semiconductor devices or eWLCSP308. Reconstituted panel 236 is singulated through encapsulant 280,insulating layers 292 and 296 of interconnect structure 290, andbackside protection layer 304. Singulating through encapsulant 280removes a portion of encapsulant 280 from a saw street while a thinlayer of encapsulant 280 remains disposed over sidewalls 148 ofsemiconductor die 124. eWLCSP 308 undergoes electrical testing before orafter singulation. Because eWLCSP 308 are singulated through encapsulant280, eWLCSP 308 are subject to less damage during singulation. With lessrisk of damage during singulation, testing can be performed prior tosingulation and expensive inspection steps can be eliminated from thefinal testing of each eWLCSP 308. By testing prior to singulatingreconstituted panel 236, eWLCSP 308 can be tested at the reconstitutedwafer level. Wafer level testing reduces cost of testing by reducing thehandling and testing time compared to pick and place handling andtesting of singulated packages.

The process of forming eWLCSP 308 on reconstituted panel 236 allows avariety of semiconductor die 124 to be processed using carrier 150,including advanced node semiconductor die with nodes down to 22 nm. Forexample, eWLCSP 308 may be formed with a greater I/O density and smallerI/O pitch that is outside the design limits for conventional WLCSP. Theprocess of forming eWLCSP 308 accommodates transitions to different I/Odensities and pitches within the same or similar packaging process usinga standardized carrier, such as carrier 150. Additionally, becauseeWLCSP 308 are singulated through encapsulant 280, eWLCSP 308 aresubject to less damage during singulation. With less risk of damageduring singulation, expensive inspection steps can be eliminated fromthe final testing of each eWLCSP 308. By testing prior to singulatingreconstituted panel 236, eWLCSP 308 can be tested at the reconstitutedwafer level. Wafer level testing reduces cost of testing by reducing thehandling and testing time compared to pick and place handling andtesting of singulated packages.

FIG. 9f shows a cross-sectional view of eWLCSP 308 after singulation.eWLCSP 308 includes encapsulant 280 formed over sidewalls 148 ofsemiconductor die 124. An interconnect structure 290 is formed overactive surface 130 of semiconductor die 124 and surface 284 ofencapsulant 280. Bumps 298 are formed over conductive layer 294 ofinterconnect structure 290. Semiconductor die 124 is electricallyconnected through conductive layers 132 and 294 to bumps 298 forexternal interconnect through interconnect structure 290. Conductivelayer 294 of interconnect structure 290 and bumps 298 remain within afootprint of semiconductor die 124 to form a fan-in package. Insulatinglayer 292 is formed over insulating layer 134 of semiconductor die 124and over encapsulant 280 to cover the interface between semiconductordie 124 and encapsulant 280 and to protect the interface duringprocessing and improve the reliability of eWLCSP 308. In anotherembodiment, interconnect structure 290 is formed completely within afootprint of semiconductor die 124. eWLCSP 308 accommodates high densityI/O and fine pitch I/O. In one embodiment, bumps 298 have a pitch P₃ ofapproximately 0.4 mm or less and a density of approximately 6 I/O mm² orgreater. In another embodiment, bumps 298 have a pitch P₃ ofapproximately 0.5 mm or less and a density of approximately 4 I/O/mm² orgreater. eWLCSP 308 may include a greater quantity of bumps 298 or asmaller pitch P₃ of bumps 298 than other packages, such as eWLCSP 272 bfrom FIG. 8g , processed on the same carrier 150. Interconnect structure290 and bumps 298 are formed closer to edge 148 of semiconductor die 124to increase the density of bumps 298. Encapsulant 280 formed oversidewalls 148 results in less damage to the device during singulationand allows for finer pitch I/O. eWLCSP 308 may include an additional rowof bumps 298, while the package structure remains similar to othereWLCSP disclosed herein, such that similar processing materials andequipment may be used to manufacture the various eWLCSP. For example,thickness T₆ of encapsulant 280 may be increased to accommodate moreinterconnections or higher density interconnections while maintaining afan-in package design for eWLCSP 308.

A thin layer of encapsulant 280 remains disposed over sidewalls 148after singulation. Encapsulant 280 is disposed over four sides ofsemiconductor die 124, i.e., over the four sidewalls 148, and backsideprotection layer 304 is disposed over back surface 128 resulting infive-sided protection of semiconductor die 124. Backside protectionlayer 304 is disposed over back surface 128 and provides mechanicalprotection for semiconductor die 124. Backside protection layer 304 mayprotect semiconductor die 124 from light. Backside protection layer 304includes a thickness T₅ over back surface 128 of semiconductor die 124and over encapsulant 280. In one embodiment, backside protection layer304 has a thickness T₅ ranging from approximately 5-150 μm. In anotherembodiment, backside protection layer 304 has a thickness T₅ of greaterthan approximately 30 μm. In yet another embodiment, backside protectionlayer 304 has a thickness T₅ of approximately 120 μm or less.Encapsulant 280 over sidewalls 148 of semiconductor die 124 includes athickness T₆, measured from a sidewall 148 of semiconductor die 124 toan edge of eWLCSP 308. In one embodiment, a thickness T₆ of encapsulant280 over sidewalls 148 is less than approximately 100 μm. In anotherembodiment, encapsulant 280 over sidewalls 148 of semiconductor die 124includes a thickness T₆ of approximately 70 μm or less. In yet anotherembodiment, a thickness T₆ of encapsulant 280 over sidewalls 148 rangesfrom approximately 30-50 μm. Backside protection layer 304 and sidewallencapsulant 280 improve the strength and reduce chipping ofsemiconductor die 124. eWLCSP 308 with backside protection layer 304 maybe formed with a reduced height or profile compared to devices with abackside encapsulant.

Encapsulant 280 and backside protection layer 304 increase the strengthof semiconductor die 124 by providing mechanical protection during thepackage assembly and singulation operations and during surface mountingand end use of eWLCSP 308. Encapsulant 280 over sidewalls 148 mitigatescracking and chipping of semiconductor die 124 within eWLCSP 308. Anopaque encapsulant 280 and backside protection layer 304 further protectsemiconductor die 124 from degradation due to exposure to light or otheremissions. Alternatively, a transparent or translucent encapsulant 280and backside protection layer 304 provide light transmission forsemiconductor die 124 having optical properties. The small footprint ofeWLCSP 308 is similar in size to a WLCSP without sidewall protection,because thickness T₆ of encapsulant 280 over sidewalls 148 results in anegligible increase in package size for eWLCSP 308. In one embodiment,the package footprint size of eWLCSP 308 is within 100 μm in the x- andy-directions of a WLCSP without sidewall encapsulant. Additionally,eWLCSP 308 formed on reconstituted panel 236 has shorter testing time, agreater yield, and lower manufacturing cost than standard wafer-leveldevices.

FIGS. 10a-10c show a cross-sectional view of a portion of semiconductorwafer 110 from FIG. 2a . Each semiconductor die 114 from FIG. 2b andshown in FIG. 10a has a back or non-active surface 310 and an activesurface 312 containing analog or digital circuits implemented as activedevices, passive devices, conductive layers, and dielectric layersformed within the die and electrically interconnected according to theelectrical design and function of the die. For example, the circuit mayinclude one or more transistors, diodes, and other circuit elementsformed within active surface 312 to implement analog circuits or digitalcircuits, such as DSP, ASIC, MEMS, memory, or other signal processingcircuit. In one embodiment, active surface 312 contains a MEMS, such asan accelerometer, strain gauge, microphone, or other sensor responsiveto various external stimuli. Semiconductor die 114 may also containIPDs, such as inductors, capacitors, and resistors, for RF signalprocessing. Back surface 310 of semiconductor wafer 110 may undergo anoptional backgrinding operation with a mechanical grinding or etchingprocess to remove a portion of base material 112 and reduce thethickness of semiconductor wafer 110 and semiconductor die 114.

An electrically conductive layer 314 is formed over active surface 312using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 314 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, Ti, or other suitableelectrically conductive material. Conductive layer 314 operates ascontact pads electrically connected to the circuits on active surface312. Conductive layer 314 can be formed as contact pads disposedside-by-side a first distance from the edge of semiconductor die 114, asshown in FIG. 10a . Alternatively, conductive layer 314 can be formed ascontact pads that are offset in multiple rows such that a first row ofcontact pads is disposed a first distance from the edge of the die, anda second row of contact pads alternating with the first row is disposeda second distance from the edge of the die.

A first insulating or passivation layer 316 is formed over semiconductordie 114 and conductive layer 314 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 316contains one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, HfO2,BCB, PI, PBO, or other polymer or dielectric material having similarstructural and insulating properties. A portion of insulating layer 316is removed by LDA using a laser or an etching process through apatterned photoresist layer to expose conductive layer 314 and providefor subsequent electrical interconnect.

Semiconductor wafer 110 undergoes electrical testing and inspection aspart of a quality control process. Manual visual inspection andautomated optical systems are used to perform inspections onsemiconductor wafer 110. Software can be used in the automated opticalanalysis of semiconductor wafer 110. Visual inspection methods mayemploy equipment such as a scanning electron microscope, high-intensityor ultra-violet light, or metallurgical microscope. Semiconductor wafer110 is inspected for structural characteristics including warpage,thickness variation, surface particulates, irregularities, cracks,delamination, and discoloration.

The active and passive components within semiconductor die 114 undergotesting at the wafer level for electrical performance and circuitfunction. Each semiconductor die 114 is tested for functionality andelectrical parameters, as shown in FIG. 10b , using a test probe head320 including a plurality of probes or test leads 322, or other testingdevice. Probes 322 are used to make electrical contact with nodes orconductive layer 314 on each semiconductor die 114 and provideelectrical stimuli to contact pads 314. Semiconductor die 114 respondsto the electrical stimuli, which is measured by computer test system 324and compared to an expected response to test functionality of thesemiconductor die. The electrical tests may include circuitfunctionality, lead integrity, resistivity, continuity, reliability,junction depth, ESD, RF performance, drive current, threshold current,leakage current, and operational parameters specific to the componenttype. The inspection and electrical testing of semiconductor wafer 110enables semiconductor die 114 that pass to be designated as a KGD foruse in a semiconductor package.

In FIG. 10c , semiconductor wafer 110 is singulated through saw street116 using a saw blade or laser cutting tool 326 into individualsemiconductor die 114. After singulation, side surfaces 328 ofsemiconductor die 114 are exposed. The individual semiconductor die 114can be inspected and electrically tested for identification of KGD postsingulation.

FIGS. 11a-11i show, in relation to FIGS. 1, 2 a, and 10 a-10 c, aprocess of forming a fan-in eWLCSP. In FIG. 11a , semiconductor die 114from FIG. 10c are mounted to interface layer 152 and over carrier 150using, for example, a pick and place operation with active surface 312oriented toward the carrier. Semiconductor die 114 are placed ontocarrier 150 separated by a gap 330 with distance D₆ betweensemiconductor die 114. Distance D₆ between semiconductor die 114 isselected based on the design and specifications of the semiconductorpackage to be processed. Distance D₆ between semiconductor die 114allows for a thin protective layer of an encapsulant to remain oversidewalls 328 after singulation. In one embodiment, distance D₆ issufficient to provide sidewall coverage by an encapsulant plus a sawstreet area 336 for singulation. For example, to produce 30 μm ofsidewall coverage for each semiconductor die 114 and an 80 μm saw street336 for singulation, the distance D₆ of gap 330 is approximately 140 μm.In another embodiment, distance D₆ between semiconductor die 114 is 100μm or less. In yet another embodiment, distance D₆ between semiconductordie 114 is greater than approximately 100 μm. Distance D₆ of gap 330between semiconductor die 114 on carrier 150 is optimized formanufacturing the semiconductor packages at the lowest unit cost.

FIG. 11a shows semiconductor die 114 mounted to interface layer 152 ofcarrier 150 as reconstituted panel or reconfigured wafer 332.Reconstituted wafer or panel 332 can be processed into many types ofsemiconductor packages, including eWLB, fan-in WLCSP, eWLCSP, fan-outWLCSP, flipchip packages, 3D packages, PoP, or other semiconductorpackages. Semiconductor die 114 are selected from KGD for mounting tocarrier 150. The use of KGD for semiconductor die 114 in reconstitutedpanel 332 improves the yield of the resulting semiconductor packages.

Reconstituted panel 332 is configured according to the specifications ofthe resulting semiconductor package. In one embodiment, semiconductordie 114 are placed on carrier 150 in a high-density arrangement, i.e.,300 μm apart or less, for processing fan-in devices. The larger surfacearea of carrier 150 accommodates more semiconductor die 114 and lowersmanufacturing cost as more semiconductor die 114 are processed perreconstituted panel 332. The number of semiconductor die 114 mounted tocarrier 150 can be greater than the number of semiconductor die 114singulated from semiconductor wafer 110. Carrier 150 and reconstitutedpanel 332 provide the flexibility to manufacture many different types ofsemiconductor packages using different size semiconductor die 114 fromdifferent sized semiconductor wafers 110.

In FIG. 11b , an encapsulant or molding compound 334 is deposited oversemiconductor die 114 and carrier 150 as an insulating material using apaste printing, compressive molding, transfer molding, liquidencapsulant molding, vacuum lamination, spin coating, or other suitableapplicator. Encapsulant 334 includes polymer composite material, such asepoxy resin with filler, epoxy acrylate with filler, or polymer withproper filler. Encapsulant 334 is non-conductive and environmentallyprotects the semiconductor device from external elements andcontaminants. In one embodiment, encapsulant 334 includes an opaquematerial and is dark or black in color to provide protection ofsemiconductor die 114 from light and to prevent soft errors byattenuating photon injection. Encapsulant 334 is deposited into gap 330and covers side surfaces 328 of semiconductor die 114, while activesurface 312 is oriented toward carrier 150 and remains protected.Encapsulant 334 is formed with a back surface 338 over reconstitutedpanel 332 and covers back surface 310 of semiconductor die 114.Encapsulant 334 contacts interface layer 152 such that surface 340 ofencapsulant 334, opposite back surface 338, is formed coplanar withactive surface 312 of semiconductor die 114.

In FIG. 11c , temporary carrier 150 and interface layer 152 are removedby chemical etching, mechanical peel-off, CMP, mechanical grinding,thermal bake, laser scanning, or wet stripping. Temporary carrier 150and interface layer 152 are removed from over surface 340 of encapsulant334 and active surface 312 of semiconductor die 114 to expose conductivelayer 314, insulating layer 316, and surface 340 of encapsulant 334.

An insulating or passivation layer 350 is formed over insulating layer316 and conductive layer 314 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 350 canbe one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxybased photosensitive polymer dielectric, low temperature (≤200° C.)curable polymer, or other material having similar insulating andstructural properties. In one embodiment, insulating layer 350 includesa low temperature curing photosensitive dielectric polymer with orwithout insulating fillers cured at less than 200° C. Insulating layer350 is formed over active surface 312 of semiconductor die 114 andsurface 340 of encapsulant 334. A portion of insulating layer 350 isremoved by an etching process with a patterned photoresist layer or byLDA to expose conductive layer 314 with respect to insulating layer 350.In another embodiment, a portion of insulating layer 350 is also removedfrom over encapsulant 334 such that surface 340 of encapsulant 334 isexposed with respect to insulating layer 350. In yet another embodiment,insulating layer 350 is formed entirely within a footprint ofsemiconductor die 114 and does not extend beyond the footprint ofsemiconductor die 114 and over surface 340 of encapsulant 334. In otherwords, a peripheral region of semiconductor die 114 adjacent tosemiconductor die 114 is devoid of insulating layer 350. In oneembodiment, insulating layer 252 includes a thickness ranging fromapproximately 7-11 μm.

In FIG. 11d , an electrically conductive layer 352 is formed overinsulating layer 350 and contact pads 314 using a patterning and metaldeposition process such as PVD, CVD, sputtering, electrolytic plating,and electroless plating. Conductive layer 352 can be one or more layersof Al, Cu, Sn, Ni, Au, Ag, or other suitable electrically conductivematerial. Conductive layer 352 operates as an RDL to redistribute theelectrical signals of semiconductor die 114. Conductive layer 352 isformed within a footprint of semiconductor die 114 and does not extendbeyond the footprint of semiconductor die 114 or over surface 340 ofencapsulant 334. In other words, a peripheral region of semiconductordie 114 adjacent to semiconductor die 114 is devoid of conductive layer352. One portion of conductive layer 352 is electrically connected tocontact pads 314 of semiconductor die 114. Other portions of conductivelayer 352 can be electrically common or electrically isolated dependingon the design and function of the semiconductor device. In oneembodiment, conductive layer 352 includes a thickness ranging fromapproximately 7-10 μm.

An insulating or passivation layer 354 is formed over insulating layer350 and conductive layer 352 using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. Insulating layer 354 canbe one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, BCB, epoxybased photosensitive polymer dielectric, low temperature (≤200° C.)curable polymer, or other material having similar insulating andstructural properties. In one embodiment, insulating layer 354 includesa low temperature curing photosensitive dielectric polymer with orwithout insulating fillers cured at less than 200° C. Insulating layer354 is formed over active surface 312 of semiconductor die 114 andsurface 340 of encapsulant 334. A portion of insulating layer 354 isremoved by an etching process with a patterned photoresist layer or byLDA to expose conductive layer 352 with respect to insulating layer 354.In another embodiment, a portion of insulating layer 350 is also removedfrom over encapsulant 334 such that surface 340 of encapsulant 334 isexposed with respect to insulating layer 354. In yet another embodiment,insulating layer 354 is formed entirely within a footprint ofsemiconductor die 114 and does not extend beyond the footprint ofsemiconductor die 114 and over surface 340 of encapsulant 334. In otherwords, a peripheral region of semiconductor die 114 adjacent tosemiconductor die 114 is devoid of insulating layer 354. In oneembodiment, insulating layer 354 includes a thickness ranging fromapproximately 7-11 μm.

Insulating layers 350 and 354 together with conductive layer 352constitute a build-up interconnect structure 356. Interconnect structure356 is formed over active surface 312 of semiconductor die 114 anddirectly on conductive layer 312 and insulating layer 316. Interconnectstructure 356 may include fewer or additional conductive and insulatinglayers. In one embodiment, the electrical interconnection ofinterconnect structure 356 remains entirely within a footprint ofsemiconductor die 114. A peripheral region outside a footprint ofsemiconductor die 114 is devoid of electrical interconnect therebyresulting in a fan-in interconnect structure 356.

In FIG. 11e , an electrically conductive layer 358 is optionally formedover the exposed portion of conductive layer 352 and over insulatinglayer 354 after final repassivation using PVD, CVD, evaporation,electrolytic plating, electroless plating, or other suitable metaldeposition process. Conductive layer 358 can be Al, Ti, titaniumtungsten (TiW), Cu, Sn, Ni, Au, Ag, W, or other suitable electricallyconductive material. Conductive layer 358 operates as an under bumpmetallization (UBM) layer electrically connected to conductive layer352. UBM layer 358 can be a multi-metal stack with adhesion layer,barrier layer, and seed or wetting layer. The adhesion layer is formedover conductive layer 358 and can be titanium nitride (TiN), Ti, TiW,Al, or chromium (Cr). The barrier layer is formed over the adhesionlayer and can be tantalum nitride (TaN), nickel vanadium (NiV), platinum(Pt), palladium (Pd), Ni, TiW, Ti, or chromium copper (CrCu). Thebarrier layer inhibits the diffusion of Cu into the active area ofsemiconductor die 114. The seed layer is formed over the barrier layerand can be Cu, Ni, NiV, Au, or Al. UBM layer 358 provides a lowresistive interconnect to conductive layer 352, as well as a barrier tosolder diffusion and seed layer for solder wettability. UBM layer 358further constitutes a portion of interconnect structure 356.

An electrically conductive bump material is deposited over conductivelayer 358 of interconnect structure 356 and is electrically connected toconductive layer 314 using an evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, and combinationsthereof, with an optional flux solution. For example, the bump materialcan be eutectic Sn/Pb, high-lead solder, or lead-free solder. The bumpmaterial is bonded to conductive layer 358 using a suitable attachmentor bonding process. In one embodiment, the bump material is reflowed byheating the material above its melting point to form spherical balls orbumps 360. In some applications, bumps 360 are reflowed a second time toimprove electrical contact to UBM layer 358. The bumps can also becompression bonded to UBM layer 358. Bumps 360 represent one type ofinterconnect structure that can be formed over UBM layer 358. Theinterconnect structure can also use bond wires, stud bump, micro bump,or other electrical interconnect.

In FIG. 11f , reconstituted panel 332 undergoes an optional backgrindingstep. A backgrinding tape or support tape 362 is applied overinterconnect structure 356 and in contact with insulating layer 354 andbumps 360. A portion of encapsulant 334 is removed in a grindingoperation with grinder 364 to planarize the surface of encapsulant 334and expose back surface 310 of semiconductor die 114. A chemical etch orCMP process can also be used to planarize encapsulant 334 and to removemechanical damage resulting from the grinding operation. The removal ofa portion of encapsulant 334 leaves new back surface 366 of encapsulant334. Encapsulant 334 is completely removed from over back surface 310 ofsemiconductor die 114 to expose back surface 310 of semiconductor die114. After backgrinding, a new back surface 366 of encapsulant 334 iscoplanar with back surface 310 of semiconductor die 114. Reconstitutedpanel 332 has a reduced thickness after the backgrinding operation. Athickness of semiconductor die 114 can also be reduced by thebackgrinding operation. In one embodiment, a portion of back surface 310of semiconductor die 114 is removed to thin semiconductor die 114 duringthe backgrinding operation. Removing a portion of encapsulant 334reduces warpage of reconstituted panel 332. Laser marking can be applieddirectly to back surface 310 of semiconductor die 114 for alignment andsingulation.

In FIG. 11g , a backside protection layer 368 is formed over backsurface 310 of semiconductor die 114 and surface 366 of encapsulant 334for protection of semiconductor die 114. Backside protection layer 368may contain one or more layers of photosensitive low curing temperaturedielectric resist, photosensitive composite resist, laminate compoundfilm, resin matrix composite sheet with filler or glass fiber cloth,resin matrix composite sheet with both filler and glass fiber cloth,insulation paste with filler, solder mask resist film, liquid moldingcompound, granular molding compound, polyimide, BCB, SiO2, Si3N4, SiON,Ta2O5, Al2O3, prepreg, or other dielectric material having similarinsulating and structural properties. Backside protection layer 368 isdeposited using spin coating, screen printing, spray coating, vacuum orpressure lamination with or without heat, transfer molding, or othersuitable process. In one embodiment, backside protection layer 368 is alow temperature curing photosensitive dielectric polymer with or withoutinsulating fillers cured at less than 200° C. In another embodiment,backside protection layer 368 is cured by UV. Alternatively, backsideprotection layer 368 is a metal layer, such as Cu foil, applied to abackside of reconstituted panel 332. Backside protection layer 368contacts back surface 310 of semiconductor die 114 to transfer heat fromsemiconductor die 114 and improve the thermal performance of the device.

Backside protection layer 368 is formed after singulation ofsemiconductor wafer 110 and reconstitution of semiconductor die 114, andprior to singulation of reconstituted panel 332. In one embodiment,backside protection layer 368 includes an opaque material and is dark orblack in color to provide protection of semiconductor die 114 fromphotons from light and other emissions to reduce soft errors. Backsideprotection layer 368 can be used for laser marking reconstituted panel332 and improves visibility of marking on the back surface of thereconstituted panel 332. In another embodiment, backside protectionlayer 368 includes a transparent or translucent material.

For semiconductor die 114 with optical properties, such as an LED, atransparent backside protection 368 layer allows photon emission fromback surface 310 of semiconductor die 114 through backside protectionlayer 368. In one embodiment, the base material 112 of semiconductor die114 includes sapphire, and semiconductor die 114 includes activeelements on active surface 312. In a flip-chip application, light may beemitted through backside protection layer 368 and through base material112 of semiconductor die 114. Back surface 310 of semiconductor die 114is coated with a translucent or transparent backside protection layer368. The translucent or transparent backside protection layer 368provides mechanical protection of semiconductor die 114, while allowinglight transmission through backside protection layer 368.

In FIG. 11h , reconstituted panel 332 is singulated with saw blade orlaser cutting device 370 into individual semiconductor devices or eWLCSP372. Reconstituted wafer 332 is singulated through encapsulant 334 andbuild-up interconnect structure 356. Singulating through encapsulant 334removes a portion of encapsulant 334 from saw street 336 while a thinlayer of encapsulant 334 remains over sidewalls 328 of semiconductor die114. eWLCSP 372 undergoes electrical testing before or aftersingulation. Because eWLCSP 372 are singulated through encapsulant 334,eWLCSP 372 are subject to less damage during singulation. With less riskof damage during singulation, testing can be performed prior tosingulation and expensive inspection steps can be eliminated from thefinal testing of each eWLCSP 372. By testing prior to singulatingreconstituted panel 332, eWLCSP 372 can be tested at the reconstitutedwafer level. Wafer level testing reduces cost of testing by reducing thehandling and testing time compared to pick and place handling andtesting of singulated packages.

FIG. 11i shows a cross-sectional view of eWLCSP 372 after singulation.Interconnect structure 356 is formed over active surface 312 ofsemiconductor die 114 and surface 340 of encapsulant 334. Bumps 360 areformed over conductive layer 358 of interconnect structure 356.Semiconductor die 114 is electrically connected through conductivelayers 314 and 352 and UBM layer 358 to bumps 360 for externalinterconnect through interconnect structure 356. Interconnect structure356 and bumps 360 remain within a footprint of semiconductor die 114 toform a fan-in package. In one embodiment, interconnect structure 356 isformed a distance D₇ from sidewall 328 of semiconductor die 114, anddistance D₇ is at least 1 μm.

A thin layer of encapsulant 334 remains disposed over sidewalls 328after singulation. Encapsulant 334 is disposed over four sides ofsemiconductor die 114, i.e., over the four sidewalls 328, and backsideprotection layer 368 is disposed over back surface 310 resulting infive-sided protection of semiconductor die 114. Backside protectionlayer 368 is disposed over back surface 310 and provides mechanicalprotection for semiconductor die 114. Backside protection layer 368 mayprotect semiconductor die 114 from light. Backside protection layer 368includes a thickness T₇ over back surface 310 of semiconductor die 114and over encapsulant 334. In one embodiment, backside protection layer368 has a thickness T₇ ranging from approximately 5-150 μm. In anotherembodiment, backside protection layer 368 has a thickness T₇ of greaterthan approximately 30 μm. In yet another embodiment, backside protectionlayer 368 has a thickness T₇ of approximately 120 μm or less. Backsideprotection layer 368 and sidewall encapsulant 334 improve the strengthand reduce chipping of semiconductor die 114. eWLCSP 372 with backsideprotection layer 368 may be formed with a reduced height or profilecompared to devices with a backside encapsulant.

Encapsulant 334 and backside protection layer 368 increase the strengthof semiconductor die 114 by providing mechanical protection during thepackage assembly and singulation operations and during surface mountingand end use of eWLCSP 372. Encapsulant 334 over sidewalls 328 mitigatescracking and chipping of semiconductor die 114 within eWLCSP 372. Anopaque encapsulant 334 and backside protection layer 368 further protectsemiconductor die 114 from degradation due to exposure to light or otheremissions. Alternatively, a transparent or translucent encapsulant 334and backside protection layer 368 provide light transmission forsemiconductor die 114 having optical properties.

FIGS. 12a-12b show another view of fan-in eWLCSP 372. FIG. 12a shows aplan view of the interconnect side of eWLCSP 372. Encapsulant 334 isformed over each sidewall 328 to form a thin peripheral ring ofencapsulant 334 around semiconductor die 114. The small footprint ofeWLCSP 372 is similar in size to a WLCSP without sidewall protection,because thickness T₈ of encapsulant 334 over sidewalls 328 results in anegligible increase in package size for eWLCSP 372. In one embodiment,the package footprint size of eWLCSP 372 is within 100 μm in the x- andy-directions of a WLCSP without sidewall encapsulant. Additionally,eWLCSP 372 formed on reconstituted panel 332 has shorter testing time, agreater yield, and lower manufacturing cost than standard wafer-leveldevices.

FIG. 12b shows additional detail of eWLCSP 372 from FIG. 12a .Encapsulant 334 over sidewalls 328 of semiconductor die 114 includes athickness T₈, measured from a sidewall 328 of semiconductor die 114 toan edge 374 of eWLCSP 372. In one embodiment, a thickness T₈ ofencapsulant 334 over sidewalls 328 is less than approximately 100 μm. Inanother embodiment, encapsulant 334 over sidewalls 328 of semiconductordie 114 includes a thickness T₈ of approximately 70 μm or less. In yetanother embodiment, a thickness T₈ of encapsulant 334 over sidewalls 328ranges from approximately 30-50 μm.

eWLCSP 372 accommodates high density I/O and fine pitch I/O. In oneembodiment, bumps 360 may include a size or diameter of approximately250 μm. Bumps 360 have a pitch of approximately 0.4 mm or less and adensity of approximately 6 I/O/mm2 or greater. In another embodiment,bumps 360 have a pitch of approximately 0.5 mm or less and a density ofapproximately 4 I/O/mm2 or greater.

FIG. 13 shows an eWLCSP 380 with an exposed back surface 310 ofsemiconductor die 114. Semiconductor die 114 includes conductive layer314 and insulating layer 316 formed over active surface 312 withopenings in insulating layer 316 formed over conductive layer 314.Encapsulant 334 is deposited over and around semiconductor die 114, andencapsulant 334 is removed from over back surface 310 of semiconductordie 114. Interconnect structure 356 includes conductive layers 352 and358 and insulating layers 350 and 354 and is formed over active surface312 of semiconductor die 114. Bumps 360 are formed over UBM layer 358 ofinterconnect structure 356. Semiconductor die 114 is electricallyconnected through conductive layers 314 and 352 and UBM layer 358 tobumps 360 for external interconnect through interconnect structure 356.Interconnect structure 356 and bumps 360 remain within a footprint ofsemiconductor die 114 to form a fan-in package. In one embodiment,interconnect structure 356 is formed a distance D₇ from sidewall 328 ofsemiconductor die 114, and distance D₇ is at least 1 μm.

A thin layer of encapsulant 334 remains disposed over sidewalls 328 ofsemiconductor die 114 after singulation. Encapsulant 334 over sidewalls328 of semiconductor die 114 includes a thickness T₈, measured fromsidewall 328 of semiconductor die 114 to an edge 384 of eWLCSP 380.Encapsulant 334 over sidewalls 328 has a thickness T₈ of less thanapproximately 100 μm. Encapsulant 334 is disposed over four sides ofsemiconductor die 114, i.e., over the four sidewalls 328. Encapsulant334 disposed over sidewalls 328 increases the strength of semiconductordie 114 by providing mechanical protection during the package assemblyand singulation operations and during surface mounting and end use ofeWLCSP 380. Encapsulant 334 over sidewalls 328 mitigates cracking andchipping of semiconductor die 114 within eWLCSP 380. eWLCSP 380 with anexposed back surface 310 of semiconductor die 114 has a reduced heightor profile compared to devices with a backside protection layer. Thesmall footprint of eWLCSP 380 is similar in size to a WLCSP withoutsidewall protection, because thickness T₈ of encapsulant 334 oversidewalls 328 results in a negligible increase in package size foreWLCSP 380. In one embodiment, the package footprint size of eWLCSP 380is within 100 μm in the x- and y-directions of a WLCSP without sidewallencapsulant. Additionally, eWLCSP 380 formed on a reconstituted panelhas shorter testing time, a greater yield, and lower manufacturing costthan standard wafer-level devices.

FIG. 14 shows an eWLCSP 390 with backside encapsulant. Semiconductor die114 includes conductive layer 314 and insulating layer 316 formed overactive surface 312 with openings in insulating layer 316 formed overconductive layer 314. Encapsulant 334 is deposited over and aroundsemiconductor die 114. Interconnect structure 356 includes conductivelayers 352 and 358 and insulating layers 350 and 354 and is formed overactive surface 312 of semiconductor die 114. Bumps 360 are formed overUBM layer 358 of interconnect structure 356. Semiconductor die 114 iselectrically connected through conductive layers 314 and 352 and UBMlayer 358 to bumps 360 for external interconnect through interconnectstructure 356. Interconnect structure 356 and bumps 360 remain within afootprint of semiconductor die 114 to form a fan-in package. In oneembodiment, interconnect structure 356 is formed a distance D₇ fromsidewall 328 of semiconductor die 114, and distance D₇ is at least 1 μm.

Encapsulant 334 is deposited over back surface 310 of semiconductor die114. Encapsulant 334 operates as a backside protection layer forsemiconductor die 114. An optional backgrinding step is used to thinencapsulant 334 over back surface 310 of semiconductor die 114. Withouta backgrinding step, the cost of manufacturing eWLCSP 390 is reduced. Athin layer of encapsulant 334 remains disposed over sidewalls 328 ofsemiconductor die 114 after singulation. Encapsulant 334 over sidewalls328 of semiconductor die 114 includes a thickness T₈, measured fromsidewall 328 of semiconductor die 114 to an edge 394 of eWLCSP 390.Encapsulant 334 over sidewalls 328 has a thickness T₈ of less thanapproximately 100 μm. Therefore, encapsulant 334 is disposed over fivesides of semiconductor die 114, i.e., over four side surfaces 328 andover back surface 310.

Encapsulant 334 disposed over sidewalls 328 and back surface 310increases the strength of semiconductor die 114 by providing mechanicalprotection during the package assembly and singulation operations andduring surface mounting and end use of eWLCSP 390. Encapsulant 334 oversidewalls 328 and back surface 310 mitigates cracking and chipping ofsemiconductor die 114 within eWLCSP 390. Encapsulant 334 furtherprotects semiconductor die 114 from degradation due to exposure to lightor other emissions. The small footprint of eWLCSP 390 is similar in sizeto a WLCSP without sidewall protection, because thickness T₈ ofencapsulant 334 over sidewalls 328 results in a negligible increase inpackage size for eWLCSP 390. In one embodiment, the package footprintsize of eWLCSP 390 is within 100 μm in the x- and y-directions of aWLCSP without sidewall encapsulant. Thus, eWLCSP 390 maintains a smallpackage size while improving the reliability of the device.Additionally, eWLCSP 390 formed on a reconstituted panel has shortertesting time, a greater yield, and lower manufacturing cost thanstandard wafer-level devices.

FIG. 15 shows another eWLCSP 396 with a backside protection layer 368.eWLCSP 396 is similar to eWLCSP 372 and includes bumps 360 formeddirectly on conductive layer or RDL 352, without a UBM layer. eWLCSP 396processed without a UBM layer further reduces the cost of manufacturingthe devices. A thin layer of encapsulant 334 remains disposed oversidewalls 328 of semiconductor die 114 after singulation. Encapsulant334 over sidewalls 328 of semiconductor die 114 includes a thickness T₈,measured from sidewall 328 of semiconductor die 114 to an edge 398 ofeWLCSP 396. Encapsulant 334 over sidewalls 328 has a thickness T₈ ofless than approximately 100 μm. Encapsulant 334 is disposed over foursides of semiconductor die 114, i.e., over the four sidewalls 328, andbackside protection layer 368 is disposed over back surface 310resulting in five-sided protection of semiconductor die 114. Backsideprotection layer 368 and sidewall encapsulant 334 improve the strengthand reduce chipping of semiconductor die 114. An opaque encapsulant 334and backside protection layer 368 further protect semiconductor die 114from degradation due to exposure to light or other emissions.Alternatively, a transparent or translucent encapsulant 334 and backsideprotection layer 368 provide light transmission for semiconductor die114 having optical properties. eWLCSP 396 with backside protection layer368 may be formed with a reduced height or profile compared to deviceswith a backside encapsulant.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed:
 1. A semiconductor device, comprising: a semiconductordie; an encapsulant deposited around the semiconductor die, wherein theencapsulant is disposed on a side surface of the semiconductor die; afirst insulating layer formed over a first surface of the semiconductordie; a fan-in interconnect structure formed over the semiconductor dieand first insulating layer, wherein the fan-in interconnect structureincludes: (a) a conductive layer formed over the semiconductor die andfirst insulating layer, and (b) a second insulating layer formed overthe conductive layer, and terminating within a footprint of thesemiconductor die; and a protection layer formed over a top surface ofthe encapsulant and coplanar with a second surface of the semiconductordie opposite the fan-in interconnect structure.
 2. The semiconductordevice of claim 1, wherein the conductive layer and second insulatinglayer are offset inwards from the side surface of the semiconductor die.3. The semiconductor device of claim 1, wherein a thickness of theencapsulant disposed on the side surface of the semiconductor die isless than 100 micrometers.
 4. The semiconductor device of claim 3,wherein the thickness of the encapsulant disposed on the side surface ofthe semiconductor die ranges from 30 to 50 micrometers.
 5. Thesemiconductor device of claim 1, wherein a thickness of the encapsulantover the semiconductor die is at least 100 micrometers.
 6. Thesemiconductor device of claim 1, further including a third insulatinglayer formed in direct contact with the first insulating layer, whereinthe conductive layer is formed over the semiconductor die, firstinsulating layer, and third insulating layer.
 7. The semiconductordevice of claim 1, wherein the protective layer includes a transparentmaterial or translucent material.
 8. The semiconductor device of claim6, wherein the conductive layer, the second insulating layer and thethird insulating layer are offset inwards from the side surface of thesemiconductor die.
 9. A semiconductor device, comprising: asemiconductor die; an encapsulant deposited on a side surface of thesemiconductor die; a first insulating layer formed over a first surfaceof the semiconductor die; an interconnect structure formed within afootprint of the semiconductor die and first insulating layer; and aprotection layer formed over a top surface of the encapsulant and over asecond surface of the semiconductor die opposite the fan-in interconnectstructure.
 10. The semiconductor device of claim 9, wherein theinterconnect structure includes: a conductive layer formed over thesemiconductor die and first insulating layer; and a second insulatinglayer formed over the conductive layer.
 11. The semiconductor device ofclaim 9, wherein a thickness of the encapsulant deposited on the sidesurface of the semiconductor die is less than 100 micrometers.
 12. Thesemiconductor device of claim 11, wherein the thickness of theencapsulant deposited on the side surface of the semiconductor dieranges from 30 to 50 micrometers.
 13. The semiconductor device of claim9, wherein a thickness of the encapsulant over the semiconductor die isat least 100 micrometers.
 14. The semiconductor device of claim 10,further including a third insulating layer formed in direct contact withthe first insulating layer, wherein the conductive layer is formed overthe semiconductor die, first insulating layer, and third insulatinglayer.
 15. A semiconductor device, comprising: a semiconductor die; anencapsulant deposited around the semiconductor die, wherein theencapsulant is disposed on a side surface of the semiconductor die; afan-in interconnect structure formed over the semiconductor die; and aprotection layer formed over a surface of the encapsulant and over asurface of the semiconductor die opposite the fan-in interconnectstructure.
 16. The semiconductor device of claim 15, further includingan insulating layer formed over a surface of the semiconductor die. 17.The semiconductor device of claim 15, wherein the fan-in interconnectstructure includes: a conductive layer formed over the semiconductordie; and an insulating layer formed over the conductive layer.
 18. Thesemiconductor device of claim 15, wherein a thickness of the encapsulantdisposed on the side surface of the semiconductor die is less than 100micrometers.
 19. The semiconductor device of claim 15, wherein athickness of the encapsulant over the semiconductor die is at least 100micrometers.